Theresa May's hopes of a Brexit trade deal with the US could be wrecked if Donald Trump is not invited to Prince Harry and Meghan Markle's wedding, the author of a blockbuster book on the President has warned.

Mr Trump will only honour the special relationship if he 'gets what he wants' – and would resent a Royal Wedding snub, according to US journalist Michael Wolff.

He also claimed that the President would abuse his planned state visit to Britain by 'Trumpalising' the Queen, hogging the limelight and treating her as though she is on one of his reality TV shows.

Author of Fire and Fury Michael Wolff (pictured) has made astonishing claims about Donald Trump's mental state, speaking exclusively to the Mail on Sunday

The comments were made by Mr Wolff in his first British newspaper interview since Mr Trump reacted with rage to the publication of Fire And Fury: Inside The Trump White House.

Speaking to The Mail on Sunday, Mr Wolff made fresh astonishing claims about the President's mental state, saying some officials believed the 71-year-old had learning disabilities or even dementia.

Others thought he could have Attention Deficit Hyperactivity Disorder (ADHD), a mental disorder often associated with children.

Mr Wolff made the comments in his first British newspaper interview since Mr Trump (pictured) reacted with rage to the book's publication

Mr Wolff revealed how Mr Trump is so ignorant about the UK that he 'had no idea what Brexit was' as late as two weeks before the referendum in 2016.

And he stood by his account of Tony Blair's secret visit to the White House – first revealed by this newspaper in March last year.

He dismissed Mr Blair's denial last week that he told Mr Trump MI6 may have spied on him.

Mr Wolff also revealed how Mr Trump is so ignorant about the UK that he 'had no idea what Brexit was' just two weeks before the referendum

Mr Wolff said the allegation came from Mr Trump himself, and claimed the former Prime Minister had been trying to 'curry favour' with the new President.

Award-winning political writer Mr Wolff, 64, said he had been 'astounded' by the global impact of his book, which was based on months inside the White House West Wing and interviews with more than 200 people, including Mr Trump and his former chief strategist Steve Bannon.

The White House has described the book as 'complete fantasy'. After a failed last-ditch legal bid to ban its publication, Mr Trump yesterday maintained his Twitter war of words with Mr Wolff, branding him a 'total loser'.

Mr Trump plans to abuse his planned state visit to Britain by 'Trumpalising' the Queen (left) and would resent not getting an invite to Prince Harry and Meghan Markle's (right) wedding, according to Wolff

But a defiant Mr Wolff stuck to his guns in an interview with The Mail on Sunday.

He warned Mrs May's controversial offer of a State visit to Britain, made weeks after Mr Trump was elected, could backfire.

It was seen as a bid to woo him into giving Britain a lucrative post Brexit Anglo-US trade deal.

But Mr Wolff claimed Mr Trump sees it purely as an opportunity to show off and outshine the Queen: 'He sees the Queen in reality TV show terms. That's the Trump modus operandi. He will try to Trumpalise the Queen and Buckingham Palace.'

And there could be more trouble if he is not on the guest list for the Royal Wedding in May.

Award-winning political writer Mr Wolff, 64, said he had been 'astounded' by the global impact of his book (pictured), which was based on months inside the White House West Wing

'He doesn't like being snubbed and wants to be the centre of attention all the time,' Mr Wolff said.

'Trump's foreign policy doctrine is simple: you Brits suck up to him and enlist in whatever geopolitical fantasy he has going, he'll give you what you want – though only if it doesn't hurt him. It is not so much vengeance, rather 'you flatter me and I'll flatter you.'

However, it is thought to be unlikely that Mr Trump will be invited to the wedding, not least because Prince Harry recently conducted a fawning interview with Barack Obama.

Ms Markle is also a big fan of Trump's defeated rival Hillary Clinton. Mr Wolff revealed how the US President had little regard for the much-vaunted special relationship between the two nations: 'If the Brits give him what he wants he will value the Brits,' he said.

'I interviewed Trump two weeks before your 2016 referendum and he had no idea what Brexit was.'

Wolff claims the self-obsessed President (pictured) craves love but cannot return it

In his book – already a bestseller in both the US and UK – Mr Wolff paints a cold picture of Mr Trump's marriage, describing how he and his wife Melania have separate bedrooms at the White House, 'the arrangement of a man who has spent his life chasing women'.

And he claims the self-obsessed President craves love but cannot return it. 'He needs love and doesn't understand when he doesn't get it,' he writes.

'He doesn't love. Other than enormous flattery, he doesn't care (about) or bond with other people.

He demands loyalty but doesn't return it.'

However, Mr Wolff offers a crumb of comfort to those who may see the claims as further evidence that Mr Trump could set off a third world war in a moment of madness. In fact, the President's selfishness makes it less likely.

'He always asks, 'What's in it for me?' He wouldn't get anything from pressing the button.'

'Blair DID hint at MI6 leaks - and Donald was source' Michael Wolff has scoffed at Tony Blair's denial that he told Donald Trump MI6 may have leaked details of his team's contacts with the Russians. Repeating the allegation made in his book Fire And Fury, Mr Wolff said that the former Prime Minister may have made the claim to 'curry favour' with Mr Trump, having once been so close to Bill and Hillary Clinton in the past. The row dates back to last March, when The Mail on Sunday revealed how Mr Blair had secretly visited the White House in a bid to win a new role as a Middle East adviser to the President. We reported how, weeks after Mr Trump's inauguration, Mr Blair held talks with the President's senior adviser Jared Kushner. Mr Kushner is married to the President's daughter Ivanka. It was seen as an audacious attempt to rebuild his career as an international statesman. Mr Wolff's book says that Mr Blair also met Mr Trump himself, as well as his then top aide, Steve Bannon. The former Prime Minister and ex-envoy to the Middle East told them he believed that British spies could have told the CIA about contacts between Mr Trump's advisers and the Russians before the presidential election in November 2016. But Mr Blair angrily denied the alleged MI6 leak last week, stating: 'This story is a complete fabrication from beginning to end. 'I've never had such conversations in the White House, outside of the White House, with Jared Kushner, with anybody else.' However, he admitted that he had discussed the Middle East with Mr Kushner at the White House. Mr Wolff laughed off Mr Blair's denial – and told The Mail on Sunday the original source of the information was actually Mr Trump himself. He said: 'For some reason Bannon and Kushner jumped into a car and went to meet the Director and Deputy Director of the CIA at its HQ in Langley to discuss what they had just heard from Tony Blair. 'Trump said, 'This is what Tony Blair has said, drive down and find out if it's true.' ' Mr Blair was 'trying to curry favour' with Mr Trump and play down his Clinton links, Mr Wolff claimed. He added: 'I was very careful how I cast it. I don't know if Blair said, 'This is what is happening' or 'In the past such things happened' or 'Have you considered the possibility?' 'I don't know the context in which he said it but I am totally confident he said it. 'I was on the couch in the White House and saw Mr Blair.' Advertisement

Mental issues? No, I'm a genius, insists furious president

Senior US officials fear Donald Trump is suffering from dementia, has learning difficulties or could even have ADHD, according to Michael Wolff.

In an explosive interview with The Mail on Sunday, the Fire And Fury author said that the White House had become a 'madhouse' under the current regime – and warned it was 'getting madder'.

The astonishing comments, which go much further than previous speculation over Mr Trump's state of mind, will infuriate the US leader.

Yesterday, in an extraordinary intervention, the President took to Twitter to defend his mental state, describing himself as a 'very stable genius'.

In a series of tweets, a clearly infuriated Mr Trump wrote: 'Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart.

'Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames.

'I went from VERY successful businessman, to top T.V. Star to President of the United States (on my first try). I think that would qualify as not smart, but genius… and a very stable genius at that!'

Senior US officials fear Donald Trump is suffering from dementia, has learning difficulties or could even have ADHD, according to Michael Wolff (pictured this week)

Mr Trump also compared the growing debate over his health to the speculation that surrounded Ronald Reagan and his fitness to be President.

He tweeted: 'Now that Russian collusion, after one year of intense study, has proven to be a total hoax on the American public, the Democrats and their lapdogs, the Fake News Mainstream Media, are taking out the old Ronald Reagan playbook and screaming mental stability and intelligence.'

But Mr Wolff insisted that the fear over Mr Trump's mental capacity was widespread in the White House, and that it had its roots in his childhood.

He said: 'He's just a rich wastrel. He was bad at school. They don't know if it is because he had learning disabilities.

'They discuss it at the White House: his apparent inability to read one page or one paragraph. He can't even follow a PowerPoint. They wonder where that is from. ADHD? A learning disability?

'They thought maybe the guy couldn't read or is semi-literate.'

White House insiders also speculated whether Mr Trump had 'the early stages of dementia', said Mr Wolff.

'Whether it's lack of sleep, the compounded effects of age… or there's actually some impairment – and that's a possibility – everybody around him discusses that.'

Mr Wolff added that he wasn't suggesting Mr Trump was 'clinically mad', but that he was so 'unpredictable and egomaniacal' the White House had become a 'madhouse'. And it was getting worse, he warned.

'Everyone around him says the symptoms have got worse in the year he has been in office – his attention span has lessened, his verbal patterns are more peculiar.

The White House exaggerates character traits. Trump came to the job with character traits weirder than other people and counter-productive to being President.'

The speculation over Mr Trump's state of mind is proving to be one of the most damaging elements of the fallout from Mr Wolff's book.

US Secretary of State Rex Tillerson was forced to state yesterday that he had 'never questioned' Mr Trump's mental fitness.