‘I’m sorry Mr Morgan, but you can’t sit in that chair. Only the President of the United States of America ever sits in that chair.’

I was in the Situation Room of Air Force One, the airplane used to fly the most powerful human being on earth around the world.

Hannah, the presidential aide tasked with escorting me around it, was very polite but also VERY firm.

‘You can in one of those,’ she suggested, pointing to one of the chairs around the Situation Room desk. ‘They swivel.’

Piers Morgan meets Donald Trump for his fourth interview with the Republican since he ran for office against Clinton

Piers stands on the tarmac outside Air Force One, the aircraft tasked with jetting Trump acroos the UK on his official visit

They certainly did swivel. I pressed a button on the sumptuous leather chair towards where the President would soon himself be sitting and imagined what it must be like in that room when all hell breaks loose.

It was this room where President George W. Bush held crisis talks on 9/11 when Air Force One was ordered to scramble him to safety after fears it would come under attack like the World Trade Centre and the Pentagon.

Opposite the President’s chair, at the other end of the room, is a giant TV screen that can beam him live into the White House Situation Room or be used to address the American people.

When the President flies on this plane, it automatically becomes the epicentre of global power.

President Trump has his very own M&Ms aboard Air Force One - and Piers bagged himself his very own

I walked slowly around the room looking out for little details that would either impress, fascinate or simply amuse.

Under the TV are three digital clocks. They permanently display the same three times – Washington DC, local time and time in the next destination. To the right of the TV was a brown leather sofa. Two hi-tech phones were behind it.

‘Can I pick one up and call someone?’ I asked, reaching down to phone Lord Sugar and boast about where I was.

‘NO!!!!!’ exclaimed another aide. ‘Do NOT touch those phones… please. Thank you, sir.’

The President’s staff all exude an air of delightfully polite menace. Next to the phones was a black leather bound menu containing that night’s culinary fare.

An onboard kitchen and chef ensure the President can eat whatever he wants, at any time of day or night, all delivered perfectly cooked and piping hot.

Try as he might, Piers was prohibited from calling Lord Sugar using President Trump's phone while aboard Air Force One for his interview

No Big Mac or fries, but personalised M&M chocolates

I was surprised to discover that the menu didn’t include a KFC bucket or Big Mac and large fries, two of Donald Trump’s favourite treats.

But then he told when we last met in Davos earlier this year that’s he been trying to eat more healthily since winning the White House 20 months ago.

So tonight’s dinner was:

Cucumber Thai salad, a medley of cucumbers, radishes, spicy red chillis, chopped peanuts, basil, cilantro and mint, tossed in a homemade vinaigrette.

Thai baked salmon fillet, baked in sweet chilli sauce over a bed of jasmine rice.

Tarte lemon bar, topped with crunchy shortbread crumbles.

The Situation Room - where President Trump makes critical decisions aboard the jet when required to do so

There was also ‘a choice of beverage’. The President doesn’t drink alcohol so that probably means his preferred diet coke.

It wasn’t all healthy though.

Further down the room lay a basket of sweets including Hershey’s Kisses chocolates (they are famously shaped like flat-bottomed teardrops – do your own jokes) and specially designed boxes of presidential M&Ms complete with Donald Trump’s signature on the back.

‘Can I take some?’ I asked an aide.

‘We’re already ahead of you, Mr Morgan,’ smiled Hannah, handing me a large bag of the M&Ms and a dozen boxes of Air Force One matchboxes. They will solve the perennial ‘what do you get someone who’s got everything?’ birthday present dilemma. Money can’t buy this stuff.

I’d arrived at Stansted Airport in Essex an hour earlier.

The whole airfield was in a massive security lockdown. It’s impossible to truly comprehend the magnitude of the machinery that surrounds the US President when he travels until you’re in the middle of it.

I went through four different security checks before reaching the tarmac.

300 Secret Service agents and a hand-polished Air Force One

There were Secret Service agents and armed British police officers everywhere; all stern-faced, and twitching. You don’t want to be the person who loses a President on your watch, even one as divisive as Donald Trump.

I once interviewed Clint Hill, the Secret Service agent who climbed on the back of JFK’s car after the President was assassinated in Dallas and he still wept 50 years later at the guilt he felt about not getting to him a second earlier to take the bullet.

That day, the Secret Service detail was just eight agents. Today, President Trump has over 300. I walked onto the tarmac and got my first glimpse of Air Force One glinting magnificently in the sunlight.

It looked perfect, which is no surprise as it is HAND-polished before every flight.

Hannah repeatedly cautioned: ‘Get what you need as fast as possible because once Marine One takes off from Windsor Castle, things will suddenly move very fast.’

We took some photos (I sent one of me standing outside AF1 to my three sons, blowing their selfie-obsessed minds. ‘OK Dad,’ said the eldest Spencer, ‘you just won Instagram.’ There can be no finer praise for a middle-aged man.)

Then I was filmed walking up the famous steps. Two Secret Service agents in dark glasses stood at the bottom, unsmiling and very serious. ‘Nice day for it,’ I observed. ‘Yes, sir,’ came the terse reply. I don’t think these guys do much small talk.

I couldn’t resist stopping at the top, turning and waving. I was later told this is technically a breach of protocol – only the President is supposed to ever do it.

But hey, Donald Trump constantly bends the rules so why can’t I? I walked inside and found a small army of uniformed personnel bustling around.

Everything looked and smelled ultra clean, which must delight a germaphobe like Trump.

‘The President will be here in 25 minutes,’ said Hannah, escorting me to the Situation Room. ‘Please tell your crew to hurry.’

There was now a controlled, super-efficient frenzy to her behavioural pattern. The ITV crew, who’d all been extensively security screened by the Secret Service, hurried.

No other plane was being allowed to take off or land from Stansted until Air Force One departed. So every second I delayed things meant thousands of members of the public being delayed. That’s an unusual burden for an interviewer who wants to get as much time as he can possibly get from the President when he arrives.

Piers holds the presidential M&Ms that travel with Donald Trump while he is aboard Air Force One

Several senior Air Force One staff came to introduce themselves. They were all chisel-jawed but extremely courteous. The kind of people who would kill you with their bare hands, but then apologise.

We shot some behind-the-scenes footage, then Hannah rushed back in.

‘OK, we need to de-clutter this room asap.’

We de-cluttered.

Outside, I noticed a long cavalcade of cars sweeping towards the plane. It carried numerous presidential staff and the White House press corps.

Woody Johnson, the new US Ambassador to Britain, came on board with his wife Suzanne. They had hosted the Trumps at their London residence and were now flying to Scotland with the President to spend the weekend at his Turnberry golf resort.

‘Relieved it’s all over?’ I laughed.

‘I’m pleased it’s been a very successful trip, Piers – yes!’ he replied, showing off his excellent new diplomatic skills. .

Suddenly, the plane’s intercom system announced it would be five minutes until the President arrived and energy levels on the plane instantly rocketed. People were streaming all over the place, making sure everything was perfectly prepared.

I looked again out of the window and saw a fleet of helicopters including Marine One sweeping down to land next to Air Force One.

Piers prepares to descend the steps of Air Force One following his interview with Donald Trump

A minute later, Trump’s chief of staff General John Kelly appeared in the Situation Room to say hello. My brother, a British Army colonel, speaks very highly of him as a military leader, and he certainly exudes an impressive air of calm authority.

‘How long do you need with the President?’ he asked.

‘As long as I can squeeze the lemon,’ I replied.

We both laughed, knowing it would be entirely at the whim of President Trump how long the lemon would allow itself to be squeezed.

Bill Shine, Trump’s new communications chief, appeared. The last man to hold his job, Anthony Scaramucci, lasted just 11 days.

‘I’ve done seven,’ Shine chuckled. ‘I need to get to at least 12 so I can beat The Mooch.’

I wished him good luck. Five days is a long time working for Donald Trump...

The 'beautiful' Queen and the 'fantastic' First Lady

Then the man himself swept in.

‘Mr President, great to see you.’

‘It’s good to see you, Piers.’

‘How are you? How was the Queen?’

‘Good, I’m very good. The Queen is FANTASTIC! She’s a fantastic woman; so much energy and smart and sharp. She was AMAZING! Such a wonderful lady and so beautiful! It was such an honour to finally meet her. To have a Queen like that is great. Come on, let’s sit down.’

I’ve known Trump for 12 years now and genuinely like him whilst disagreeing with many of the things he says and does.

He’s a uniquely impulsive and charismatic man, which as we have seen can manifest itself in both a very good and very bad way. Trump’s wife, Melania, came in too.

I saw a lot of her over the years but this was the first time since her husband became President.

She was wearing the same sleek cream Christian Dior suit she’d worn to meet the Queen.

‘First Lady! How lovely to see you again,’ I said.

‘Nice to see you too,’ she replied. ‘It’s been a long time.’

I’ve always really liked Melania. She’s not just a strikingly beautiful woman; she’s also genuinely nice and warm, but a tough cookie too.

Life must have been so hard at times for her in the past three years since Donald declared he was running for President - what with THAT tape, the Stormy Daniels saga and endless lurid headlines.

But she and Donald still seem as relaxed and happy in each other’s company as they always seemed before he went into politics.

‘I hope this doesn’t sound too patronising,’ I told her, ‘but I have great admiration for the way you have conducted yourself as First Lady. A friend of mine (Sarah Brown) did this kind of job when her husband became British Prime Minister so I know how tough it can be.’

‘I just feel it’s important to be true to yourself,’ she smiled.

Her performance under fire has resonated well with the American public who have given her very good and improving approval ratings which currently stand a lot higher than her husband’s.

I think they admire her grace and resilience under constant, and often very humiliating fire.

‘The Queen Mother always said the secret to public life was to never explain, complain or speak too often in public,’ I said.

‘That’s right,’ Melania laughed. ‘I agree with that completely. I know that quote.’

‘Hey Piers, she’s fantastic!’ said the President.

Then, after Melania left, he got into game mode.

‘OK, let’s go,’ he barked, ‘the plane’s waiting to take off!’

I’d been told we had a maximum of 15 minutes for the interview, due to the flight schedule.

That can get eaten up very quickly with Trump given his tendency to answer every question with lengthy hyperbolic boasts about how great he is and how well he’s doing.

As I’ve previously found to my cost, if you engage him too aggressively in one exchange over one issue, the plug can get pulled very swiftly.

So my Trump interview strategy, honed over at least 35 interviews with him over the years, has been to ask as many questions about as many issues as possible to get a wide range of responses.

I think that’s particularly important now he’s President, where his opinions are obviously so important.

Trump-haters will always scream blue murder that an interviewer doesn’t spend every second of his allotted time clubbing him over the head with a large hammer.

But I prefer to engage with Trump and listen to him in our interviews rather than berate and abuse him.

Our long time friendship is why I am the only British TV journalist he speaks to (this was my fourth interview with him since he ran for President, two as a candidate, two as POTUS.)

He also has a wonderful habit of speaking about me that I know drives my rivals and critics absolutely insane with rage.

‘My Piers,’ he began today, ‘How are you man? My champion!’

I laughed. ‘If you had any idea how much you saying that irritates so many people, then you’d say it more often…’

Meeting the Queen and memories of his mother

‘I tell it like it is,’ he replied, ‘You and I both. That’s our problem!’

In the end, I got 30 minutes and covered a wide range of issues and people from Theresa May, The Queen, Vladimir Putin and Kim Jong Un to abortion and immigration.

Trump was as he always is – punchy, provocative, revealing and uncompromising.

I started by asking him more about his historic meeting with The Queen at Windsor Castle.

‘That moment when you walked towards The Queen, what was going through your mind?’

‘Well first of all I was thinking about my mother. My mother passed away a while ago and she was a tremendous fan of the Queen. She thought she was a woman of elegance, and my mother felt she was a great woman. I remember even as a little guy, if there was any kind of a ceremony to do with the Queen, my mother would be watching the television - she wanted to see it.’

Trump sighed. ‘I was walking up and I was saying (to Melania) “Can you imagine my mother seeing this scene? Windsor. Windsor Castle.” And it was beautiful, it was really beautiful but the Queen is terrific. She is so sharp, so wise, so beautiful. Up close, you see she’s so beautiful. She’s a very special person. And the way she’s conducted herself for so many years. And she’s got a lotta years left.’

The Trumps spent nearly twice as long (45 minutes) with Her Majesty as they’d expected and said they got on famously.

‘It was a very easy talk,’ he said. ‘You know, it’s hard to talk to somebody if you’re, sort of, if there’s not that something special. You know that better than anybody. Sometimes you’ll have a guest on where no matter what you do it’s not working, right? And then sometimes it’s magic. We had a great, a great feeling.’

‘Did you get the feeling she liked you?”

‘Well I don’t want to speak for her, but I can tell you I liked her. So usually that helps. But I liked her a lot.’

‘What were her opening words?’

‘Um, “Welcome”. Just “Welcome”. Just very elegant. And very beautiful. It was really something special.’

‘Did you mention your mother?’

‘I did, I said: “You know, my mother was your big fan. She was born in Stornaway in The Hebrides. And that’s very serious Scotland as you know, there’s no doubt about that.’”

Trump revealed the Queen told him the names of all the presidents she had met. ‘Harry Truman was the first president that she got to meet and know, and she went through a whole list. It was a very nice moment, Piers, very nice.’

I asked if they’d discussed Brexit.

‘I did. She said it’s a very - and she’s right - it’s a very complex problem, I think nobody had any idea how complex that was going to be...Everyone thought it was going to be ‘Oh it’s simple, we join or don’t join, or let’s see what happens..’

'Did she give you any clue as to which way she thinks about it?’

Trump suddenly clammed up.

‘Well, I can’t talk, you know I’ve heard very strongly from a lot of people, you just don’t talk about that conversation with the Queen, right? You don’t wanna do that...Let me tell you what I can talk about... she is an incredible woman, she is so sharp, she is so beautiful, when I say beautiful - inside and out. That is a beautiful woman.’

‘Your mother would have been looking down …

‘She’d be very proud.’

‘When you got in Marine One afterwards with Melania and you talked about what you just experienced with the Queen, it must have been, even for a tough guy like you, quite an emotional thing?

‘It is. To have that meeting I think was really great. We met, but also watching the guard, hearing the sounds, being in that place, that very special place. it was very special there’s no question about that.’

It was clear just how much meeting the Queen meant to Trump.

He sounded about as humble as I’ve ever heard him before as he spoke about her (admittedly, his humility bar is quite low…)

We turned to the rather more controversial matter of Brexit.

Trump spectacularly blew up his trip this week with an incendiary interview in The Sun that attacked Theresa May for watering down her Brexit plan to such an extent that it might kill off hopes of a trade deal with America.

It was the political equivalent of going to someone’s house for dinner and telling them their food is inedible.

He tried to rein back on his criticism when they appeared for a joint press conference on Friday, but a lot of the damage was already done with May’s critics leaping on the belief that her new Chequers plan which caused David Davis and Boris Johnson to resign, doesn’t allow Britain to do a bi-lateral deal with America.

I've given May 'an option' to bring EU to heel

I was curious if Mrs May had managed to change his mind during their series of private meetings.

‘No, no, I think my position is the same - I just think it’s really their choice. And if you speak to the Prime Minister, she’s really saying: “No, it is Brexit, it is what it was, but we’re leaving certain things.”

‘Do you believe that?’

‘Well honestly it’s not for me to say.’

‘Most people don’t believe it.’

‘Well yeah, I know, but…’

‘They think it doesn’t allow for America to actually trade.’

‘Well that would be bad, I mean look, I think it’s worse for UK than it is for us because we’re doing very well, and we’re doing very well at trade, and we’re doing incredibly well overall, and we’re having the best numbers we’ve ever had as a country - best employment numbers, best GDP numbers.’

‘If we were free, Britain, to do a genuine free trade deal...’

‘We would make a tremendously big deal.’

‘People say: “Come on. The President of the United States, Donald Trump, he wants to put America first, we’re not going to get a great deal.”

‘That’s true. Sure, but you’re going to put UK first, and we’re going to, you know, we’re going to argue, we’re going to fight, and we’re going to end up making a deal.’

‘Is it in your interests?’

‘We are putting America first but you have to put your country first, and other people have to put their country first.’

‘The sceptic in me would say: ‘What is the incentive for America to do a great deal with the United Kingdom?”

‘We would make a great deal with the United Kingdom because they have product that we like. I mean they have a lot of great product. They make phenomenal things, you know, and you have different names - you can say “England”, you can say “UK”, you can say “United Kingdom” so many different - you know you have, you have so many different names - Great Britain. I always say: “Which one do you prefer? Great Britain? You understand what I’m saying?’

‘You know Great Britain and the United Kingdom aren’t exactly the same thing?’

‘Right, yeah. You know I know, but a lot of people don’t know that. But you have lots of different names. The fact is you make great product, you make great things. Even your farm product is so fantastic.’

Trump revealed at the press conference he had privately suggested Mrs May activate a ‘brutal option’ to bring the EU to heel.

I asked what it was.

‘Well I recommended her something, I gave her an option, I’d rather not tell you what that option is, but I think she might. I think it would’ve been great, but it’s not too late for her to do that necessarily.’

May must have a 'carve out' to secure us a trade deal

‘Can you look me in the eye Mr President and say there will be a great trade deal if we get this damn Brexit thing right?'

‘Oh I think we’re going to have a great trade deal, I’ve really no doubt about it. We’re going to get it. I said (to Theresa May), “Make sure you have a carve out, you have to have a carve out” - where no matter what happens they have the right to make a deal with the United States.’

‘I think no matter what happens, they’re going to have carve outs and they’re going to make a deal with us.’

‘I’m saying that now so that when I go into negotiations with you people, I’m going to try and top you, you’re going to try and top us. The main thing is they have to have the right to do it so that’s the only thing I told (Theresa) you have to have the right to do it. You can’t be shut out because we’re much bigger than the European Union, we’re more important from that standpoint.’

‘And has Theresa May looked you in the eye and said “We will get there?”

‘Well she feels she’s going to be able to make a deal, yeah.’

The 'sad' impact on Europe of mass immigration

At the press conference, Trump said he feared for damage to Europe’s ‘culture’ from mass immigration.

He elaborated on this with me. ‘I said Brexit was going to happen for a specific reason: immigration. I think the people of the UK want to have who they want in their country, and I think what’s happening all over Europe is very sad.’

I pressed him on his ‘culture’ comment: ‘People were surprised you said that because America of course was built on immigration. The great culture of America is that it’s full of immigrants. So why do you not think it can work in Europe?’

‘I think it depends where they are,’ he replied. ‘Who they are, educational levels, work levels, I think it depends on a lot of things. I just see what’s happening, the crime is through the roof in some places that have never had crime.

'I’m not going to mention specific countries, but you can pick the country and you can see what’s happening. Some of the countries would not take it. And they’re being really admonished by the European Union for not doing it.

'You look at Hungary as an example. They’re not agreeing to do what some of the other countries did. Now it’s a very tough thing, on a humanitarian basis you’ve got to do something, and yet it is changing Europe. It’s seriously changing Europe.

'You take a look at what’s happened in Paris, you take a look at what’s happened in London. You look at what’s going on - it’s changing Europe, and I don’t mean in a positive way. I’m not the president of Europe, I’m the president of the United States, and we have a strong border, we have a tough border. And we have a different problem, but similar in certain ways.’

As we spoke, over 100,000 anti-Trump protestors were marching through the streets of London.

‘Some of them are protesting in my favour, you know that?’ he insisted. ‘There are many, many protests in my favour.’

Hmmm. I must have missed those.

I told him many people were protesting over his recent highly controversial policy of separating children from their illegal immigrant parents if they tried to cross the border into the U.S.

‘That wasn’t my policy,’ he interrupted, ‘Obama had the same exact policy. In fact, they were showing pictures of kids separated from their parents and they say, isn’t this terrible. And it was pictures of 2014.’

It is certainly true that Obama deported over three million illegal immigrants – earning himself the grim nickname ‘Deporter-in-Chief’ in Mexico - and that numerous children were separated from their parents in the process.

But Obama did not have the ‘exact’ same ‘zero-tolerance’ policy towards illegal immigrants that Trump’s administration implemented several months ago, which started automatically prosecuting people trying to cross the border illegally and thus automatically separating them from their children who are not allowed under U.S. law to be jailed too.

Trump quickly scrapped the new policy when outrage grew.

‘As a father of five,’ I asked, ‘was there a moment when you looked at those pictures of those kids and you felt actually this is wrong, this is not the right thing to do?’

‘You’re right, and I did an executive order putting them all together.'

‘The fact you changed it, do you regret that that policy was in place?’

‘Well all I did was go by the law. But you know the parents are put in jail essentially, you know they came in illegally. Now when people come in illegally they have their kids, there are consequences to that, but I still didn’t like the idea of separation.’

Dealing with Little Rocket Man and ruthless Putin

On Monday, Trump will attend his first summit with Russian leader Vladmir Putin, in Finland.

It comes a few weeks after his extraordinary meeting with North Korean dictator Kim Jong-Un in Singapore.

‘Is this the Trump doctrine now to get in a room and try and do deals with people that have been perceived as the enemy?’ I asked.

‘I’d like to see peace. A lot of people thought I’d be, most people said well on day one we’re going to be in war as Trump as President. Well here it is - we’re getting rid of wars. We’re actually getting out of wars.’

‘Can you trust Kim Jong Un?

‘Look, all I can say is this: when President Obama was in his last couple of years all they talked about was North Korea, everybody did. I’m not blaming him, I’m just saying it was a big problem.

'The testing and all of the… But then when I got in, we took a different approach and there was plenty of testing and plenty of nuclear tests going off and missiles going up and rockets going up…. And in the last nine months, there have been no missiles tests, no nuclear tests; there’s been no nothing.

‘The cynics say he’s playing you and he just wants to be on the global stage and you’ve given him that - what do you say to those people?’

‘He was on the global stage before. What have I done? I met with him.’

‘Did you like him?’

‘I get along with him great, yeah. He’s very smart, great personality, he’s funny and tough, good negotiator…

‘He’s a ruthless dictator…’

‘Sure he is, he’s ruthless, but so are others. I mean, I could name plenty of others that we deal with that you don’t say the same thing about. I mean plenty of the people that I deal with are pretty ruthless people.’

‘Is Putin one of those?’

‘I can’t tell you that, I assume he probably is. But I could name others also. Look, if we can get along with Russia that’s a good thing. I don’t know him (President Putin). I met him a couple of times, I met him at the G20.

'I think we could probably get along very well. Somebody said are you friends or enemies? I said well it’s too early to say but right now I say we’re competitors but for the United States, and frankly the UK and other places, to get along with Russia and China and all of these other places…. Piers that’s a good thing, that’s not a bad thing. That’s a really good thing.’

As for suggestions he wants to dismantle NATO or pull America out of it to please Putin, he was scornful.

‘Piers, I don’t even know why you’re asking the question. We have now a much more solid NATO than they’ve had for years. And last year, since I was elected, we picked up 34 billion dollars extra. Now, if you add that into all the other things I’ve done, President Putin has to respect what we’ve done.’

Trump has just announced his pick for a new justice on the Supreme Court, Brett Kavanaugh – who will now go through a thorough interrogatory audition in the Senate before he can be confirmed.

There are growing concerns that a new Conservative-majority Supreme Court may move to overturn Roe Vs Wade, the case in 1973 that legalised abortion in America.

It would take a test case to be considered, which may take years to come to the court.

The US's most contentious issue... abortion

Trump, as with many things including gay marriage and guns, has flip-flopped over abortion – one of the most contentious hot button issues in the U.S.

‘Well, look, I’m a conservative as you know,’ he replied. ‘I have my views, but I’ve been told it’s truly best not to talk about it. That’s a little bit of an interesting stance but that’s the right thing to do, now…’

‘Do you you understand why women are concerned?’

‘I do understand, but I also understand that you know, that’s a 50/50 question in this country. (In fact, 2/3 of Americans recently polled do NOT want to see Roe vs Wade overturned, though 50% of American do want some restrictions on abortion). I think he (Kavanaugh) is going to be confirmed and someday in the distant future there could be a vote. There’s also a very good chance there won’t be a vote. We’ll have to see what happens. A case has to get up there. It could be a long time before a case ever gets up there.’

I asked Trump, a man used to flying on big private planes, what he thought was the coolest thing about this one.

‘I’ve known great planes, but this is Air Force One and I think the coolest thing of this plane is: it’s Air Force One. It has the best telecommunications I’ve ever seen in my life, we have defence systems, we have all sorts of things, but the coolest thing is this is Air Force One - this is it, you know?’

I knew what he mean because I’ve flown on a lot of planes, commercial and private, but never anything as cool as Air Force One.

It’s measures 4000 sq ft and is designed to operate as a mobile command centre, complete with medical operating room and a permanent doctor.

It can refuel in mid-air, technically allowing it to keep flying for days or weeks if necessary. Though one of the crew told me it rarely goes longer than 12 hours.

Air Force One flies at top speed of 600mph, almost the speed of sound and can reach a maximum altitude of 45,000 ft. (Commercial planes rarely fly higher than 30,000ft).

It seats up to 70 people, in business class comfort, and is said to be protected by everything from electronic jammers to heat-seeking missiles – even able to withstand a nuclear blast.

Still, being on it with the world’s No1 terror target was a little unsettling.

‘I can’t work out whether I should feel incredibly safe sitting here with you, or about as at risk as I’ve ever been in my life,’ I said.

Trump laughed. ‘Feel safe, be positive…’

His gratitude to Harry over Meghan's father

Last month, Meghan Markle’s father Thomas, who hates Trump, told me that Prince Harry had urged him in a phone call to ‘give Trump a chance’.

I told the President this and he looked thrilled.

‘That’s good!’

‘Do you like Harry?’

‘Yeah I like Harry, I’ve never met him, but I’ve always liked Harry. I like the whole family to be honest, they have a good energy.’

I asked Trump about his wife Melania.

‘She does an amazing job, I mean all the stresses...'

‘She does…’

‘…all the pressure, all the headlines and so on…’

‘She does..’

‘..what would you like to say about Melania?’

‘Well I’m very proud of her, she does an incredible job and you know she’s very popular.’

‘She’s more popular than you Mr President.’

‘She could very well be! I hope she never runs against me… but no, she’s done a fantastic job, she really has.’

Confirmed: He'll run for a second term in 2020

There has been lots of rampant speculation as to whether Trump will run for President again. It was time to get a definitive answer.

‘Is there any doubt you’ll run again in 2020?’

‘Well you never know what happens with health and other things…’

‘You look fit.’

‘I feel good.’

‘I saw your menu for tonight, pretty healthy stuff... but 2020, are you going to run?’

‘Well I fully intend to. It seems like everybody wants me to.’

I suspect ‘everybody’ is bordering on fake news.

But there it was – official confirmation that Donald Trump will run again.

‘Do you see a Democrat who can possibly beat you?’ I asked.

‘No. I don’t see anybody. I know them all and I don’t see anybody.

‘So liberals could be facing not two more years of you but potentially six?’

‘They do not have the right candidate.’

His love of Twitter in the fight against fake news

Love him or loathe him, Trump has transformed modern presidential communication, particularly through Twitter.

‘Did you ever think you, at 72, would be the the most skilled exponent of Twitter in the world?’ I asked.

‘Well you’re right up there, you do pretty good!’ he replied. ‘I tell you what, and you were doing it before me. I just find it’s a modern day form of communication.

'I’ll see something where somebody says something wrong, or says something right, and rather than sitting around doing nothing, I’ll be able to put out something.

'Or in some cases call and say: “put this exact statement out” I’m very exacting. From the comma, to everything. But, you’re watching and then, like two seconds later, we have ‘breaking news, Donald Trump, President Trump has just been’…. And you make a statement and such a powerful statement so quickly.’

‘Do you like that immediacy?’

‘I like the immediacy, I like the power of it because it gets the point across. I can combat that fake news because I have so many followers.

'You add it all up and it’s like over 150 million people - that’s a tremendous amount of people between Facebook and Instagram and Twitter - three different platforms, it’s tremendous. You get the word out, you can really protect yourself from the lies.’

After the interview, I presented Trump with a gift – a kilt made from his family’s tartan McLeod. He seemed genuinely moved by it. Trump feels a great affinity with the Scots because of his mother.

Now get off my plane, Piers!

‘Great to see you,’ Trump said, as we shook hands again. ‘Now get off my plane! – we’re late!’

The crew and I grabbed our stuff and raced out the back of Air Force One, past the White House Corps – knocking some of their pre-packed meals as we did so. They get charged $20 per meal apparently.

Some grinned at me in grudging admiration and shouted out ‘what did he tell you?’

Others stared jealousy-ridden daggers. Many just instantly hit their phones to tweet that I was there and had done an interview.

I brushed past National Security Advisor John Bolton who said hello but looked very preoccupied.

I can’t even imagine the stuff he gets told every day that must terrify the life out of a human being. Once off the plane, we were sped-marched away by several Secret Service agents.

There were so many other agents and armed police now. It was like a military zone. Some wore balaclavas – SAS perhaps?

I was able to film a final piece to camera as Air Force One taxied and took off. All around us, other engines were revving – the back up Air Force One, the helicopters including Marine One, and The Beast - the enormous presidential limo which can withstand rocket attacks.

I could feel the power draining away from me as the presidential machine began to move off. My moment in the cauldron of the US Presidency was over.

The next morning, I spotted a Facebook post by my brother-in-law Patrick, a former British Army colonel who taught Princes William and Harry at Sandhurst:

‘Good old Air Force One. Apparently a direct cause of my flight from Germany being delayed by over three hours. It’s 1am and I’m still on the ground..’

Oh dear. I haven’t had the heart to tell him it was my fault yet.