The only problem with hosting The Apprentice, says Baron Sugar of Clapton, is that he tends to intimidate people without meaning to. Even greeting him properly is a hurdle. I consider chancing an “Alan”, but chicken out. For the avoidance of doubt, it’s Lord Sugar to you, me and anyone else who isn’t a close friend or colleague.

Is that how he introduces himself? He looks puzzled. “Well, normally, because of the television programme, I don’t have to introduce myself. They know who I am.”

Fair enough. Sugar wasn’t exactly a shrinking violet as the boss of Amstrad in the 80s and 90s but, since 2005, The Apprentice has made him the country’s most recognisable face of business. And what a face it is. With a forehead etched into a permanent frown, his 70-year-old mug could be an emoji for “disgruntled”. He says that the boardroom postmortems last up to three hours and are quite fun, but fun doesn’t survive the editing suite. “What you see is the rough, gruff businessman. It doesn’t put bums on seats making me look nice.”

Although in photographs Sugar smiles as if someone is pressing a gun into his back and hissing at him to act normal (“I’m immune to disappointment,” he tells the Guardian’s photographer), he’s surprisingly jovial company. He keeps glancing at his brand-new Rolex, but I can’t tell whether he’s checking the time or just admiring it. He’s amused by the idea that 13 years on The Apprentice might have made him warmer and more empathetic. “No, I’m the same,” he says with a grainy chuckle. “I haven’t changed at all.”

This series of The Apprentice is the last in a three-year contract, but Sugar says he would happily sign another. As a billionaire whose fee goes to charity, he’s not in it for the money but says he likes inspiring young entrepreneurs and building new businesses with the winners. These days, though, the show is more of a guilty pleasure for viewers. Ricky Gervais, among others, has blamed it for encouraging a culture of cruelty and ruthlessness, which Sugar disputes: “I hope it sends a good message to youngsters.” More than that, it is one of the few television shows you could legitimately accuse of making the world worse, having given us Katie Hopkins and, arguably, President Trump.

“She was very mouthy,” he says of Hopkins, “but after the show she became deliberately outrageous. She’s a very bright lady. She’s no fool. It’s a shame she’s turned her mind on to being this controversial person.”

He has less insight into Donald Trump, formerly his counterpart on the US version of the show. “They ruined it in America, as they would.” Their relationship consists of one phone conversation and a juicy Twitter beef in 2012 (Trump: “Without my show you’d be nothing!” Sugar: “Shut up and argue with Obama.”). “To be fair, he arranged a very nice table for me at Mar-a-Lago on a special occasion a couple of years ago. I heard he was going to pick up the bill, but he didn’t. But never mind.”

Does he think the president is up to the job? “Why not? I think he is up to it, actually, if he didn’t open his mouth so much and put his foot in it. What I would do if it was me” – picture that for a moment – “is ask: ‘What is the issue? Tell me what it’s all about.’ And then come up with a way, if possible, to fix it. So, possibly he could do a good job if he wasn’t such a temperamental loudmouth.” He looks amused. “He thinks he’s still on The Apprentice. He chucks people out who don’t agree with him.”

The Apprentice worked wonders for Trump by convincing many Americans that he was a master dealmaker, but Sugar never considered him a good businessman. “No, he’s definitely not. But in America, anything can happen. If you owe the bank $2,000 they’ll shut you down and make you sell your house. If you owe them $2bn they’ll take you out to lunch.”

Does Sugar think he has the right personality for politics? “Nah, I haven’t got the patience.” In the House of Lords he enjoys debating his areas of expertise – technology, telecommunications, apprenticeships – but avoids the rest. Frontline politics strikes him as an ordeal. Being prime minister is “a thankless, hopeless task. People are always complaining about something.”

He still likes Gordon Brown, who made him the government’s enterprise tsar, and a life peer, in 2009. Sugar was a New Labour man through and through and admired Brown for stanching the wound of the banking crisis a decade ago. “The poor fella took over from Blair and bang! The world collapsed. When historians look back, some of the moves he made were actually brilliant. He was unlucky.”

David Cameron offered Sugar the same job last year, but Theresa May took over before he could get started. “She walked in and that was it. It just went …” He slopes his hand in a nosediving gesture. He doesn’t exactly look heartbroken.

Cameron made the offer because Sugar had publicly left the Labour party after 18 years. He thought they had chosen the wrong Miliband and tacked too far to the left, but he didn’t want to quit before the 2015 election in case it hurt the party, so he waited. Is he a Tory now? “No! Absolutely not. I’m neutral.” He’s about to be officially designated a crossbench peer and, as a lord, he can’t vote. “Don’t ask me who I would have voted for.”

When I ask him if there are any active politicians who impress him, a smaller frown forms inside the permanent one. He can’t think of anyone, although he has changed his mind about Sadiq Khan, the mayor of London, whom he accused last year of “single-handedly wreck[ing] the Labour party”. “To be fair, I wasn’t very kind to him, but he seems to be doing a reasonably good job.”

Sugar weighs up the last election like it was a particularly disappointing Apprentice task that both teams failed. He says the Tory campaign was “absolutely terrible,” contrasting footage of Corbyn’s euphoric rallies with shots of May “with about 10 people standing around in a market square”. He wonders who could replace her. “Not that clown,” he says, pausing. Johnson? “Johnson. I mean, he is a clown, but he’s got a bit of a mouth on him and I suppose if he carries on lying like he did with Brexit he might swing people round.”

Labour’s unforeseen resurgence has not improved his dismal opinion of Jeremy Corbyn. “All they’ve done with Corbyn is they’ve taken him to Matalan, they’ve bought him a suit, they’ve cut his hair and they’ve cleaned him up a little bit. He looked like a real lefty hippy when he first came on the scene. So they’ve dressed him up, told him what to say and he’s become a proper politician now – in other words, a liar.”

Sugar has a thing about liars. In the first ever episode of The Apprentice he spelled out his bugbears: liars, cheats, bullshitters and schmoozers. Asked what gives business a bad name he has a similar answer: “Cheating. Lying. Fraud. Tax avoidance.” Last year, he sued the Daily Mail for calling him a “spiv” and donated his £20,000 award for damages to Great Ormond Street children’s hospital.

“My associate and friend Piers Morgan said: ‘Don’t do it. You’ll wind them up. They’ll go after you.’ And I said: ‘Well, sod ’em. If they keep writing lies about me I will keep going to my lawyer and we’ll keep whacking ’em and Great Ormond Street will get another MRI scanner.’ They’re bloody liars. Liars! And absolutely vindictive.”

Associate and friend? I’ve never quite understood the relationship between Sugar and Morgan. During their frequent Twitter spats, they appear to feel genuine antipathy, but apparently not. “It’s a funny relationship, really. We’ll sit down and have dinner and when we’re in the public arena we like to have a fight so I don’t know what you’d call it. It’s a bit mad, isn’t it? He deserves a good slapping every so often because he talks such a load of rubbish sometimes.” He smacks a fist into his palm. “You get carried away.”

Like Trump and Corbyn, Brexit is something Sugar didn’t see coming. He had been critical of the EU and thought Cameron should have been a tougher negotiator, but he never thought we would vote to leave. “I think what happened was – no disrespect to middle England – they didn’t understand what they were voting for. But I tell you what, in five years’ time when it’s all sorted out they are not going to like themselves because it’s going to be an absolute nightmare.”

Sugar is a brisk pragmatist who sees politics as a matter of fixing problems and getting things done. He has no instinct for more primal, populist concerns that stir the blood. Does he feel out of step with politics now? “It’s very emotional now,” he agrees. “It’s brought about by what the person promises, even though he or she can’t deliver whatever it is. We’ve seen that with Corbyn and with Trump. Trump says what people want to hear: immigration’s doing you in, jobs we’re losing, China’s killing us, Mexican wall. He’s not going to deliver any of it. But there you are. The truck driver and his wife voted because they believed what he said.”

Another of his blind spots is the gender pay gap. He sees the world through the prism of his own experience, starting out with £100 exactly 50 years ago and building an empire, and his staunch belief in meritocracy leaves no room for concepts such as systemic bias and structural inequality. In life, as in The Apprentice, good workers are rewarded and bad ones aren’t. Can it be that simple? Yes, he insists. Look at the US. “What’s the name of that famous black lady?”

Oprah Winfrey?

“Oprah Winfrey. There’s another lady, the one with the short hair.”

“Ellen DeGeneres?” offers one of the men in suits.

Sugar looks unconvinced. “Yeah, all right. Her then. She must get paid a bloody fortune because she has a USP. That’s what people pay for.”

We’re not getting very far and anyway, the Rolex says our time is up. “Good show,” he says cheerfully. “Got enough?” I tell him he succeeded in not being intimidating and he chuckles again. “I told you I’m an easygoing person.”

The Apprentice is on BBC1 on Wednesday at 9pm