SUITED and booted in the boardroom, a formidable business mogul, uttering that iconic line: 'You're fired!'... that's the image of Lord Alan Sugar I have in my head. And when I first meet him, looking at his body language alone, he lives up to those expectations.

He's leaning right back on the sofa, arms crossed tightly across his chest, and he looks at me across the table... almost impatiently. I'm half expecting him to ask to see my CV, Apprentice-style. But you know what I didn't envision? Lord Sugar pedalling along on a bicycle.

"I fly airplanes, I cycle my bike," the 70-year-old TV star reveals. "I'm always a five-day-a-week man, weekends I never work, apart from special occasions where there's exhibitions or seminars or something like that."

The London-born entrepreneur, who set up his first business – electronics company Amstrad – aged 21, also cracks more smiles than anticipated throughout our chat. And he's especially animated when talking about mentoring the winners of past series of The Apprentice, currently half-way through its 13th series.

So, off-screen, is the intimidating Lord Sugar actually a bit of a softie at heart? "Oh, real softie, absolutely; you should ask my wife," he says. "That's one of the problems of The Apprentice is that people are a little reluctant to talk to me because they think that... The way I'm edited is it comes across as I'm a bit abrupt and blunt and all that stuff. But that's not really me in real life," adds Lord Sugar, who married wife Ann in 1968, and has three children and seven grandchildren.

The Apprentice's much-loved format has stayed largely the same since series six onwards – each week, the candidates (there are 18 to start with) are split into two teams to tackle a business task set by Lord Sugar and his two aides, Baroness Karren Brady and Claude Littner. Whichever group loses the task endures a grilling from Lord Sugar in the boardroom, and then at least one person is fired from the process each week. Interview week sees the remaining candidates' CVs and business plans torn apart, before the final episode sees the winner given £250,000 investment from Lord Sugar in their business.

"As you've seen with other programmes, when people start to try and tinker with things, it ends up as disastrous," he says, when asked if he feels pressure to keep the show fresh. "If it's not broke, you don't fix it."

The 13th series has involved tasks such as creating a range of burgers and planning a premium corporate experience at a sports event (with some entertaining results), tense confrontations between team members and many larger than life contestants.

Big personalities who have starred on the show in the past have gone on to forge reality TV careers, with people like Katie Hopkins and Luisa Zissman entering the Celebrity Big Brother House. But Lord Sugar maintains the casting process hasn't changed, and that people don't apply to the show for fame.

"What happens is they get withdrawal symptoms after being seen on TV and they get head-hunted by the producers of these other programmes," he explains. "Those producers know they're just going to use them, for one series, and then just throw them away. It's just human nature isn't it, 'I wanna be back on television'. So that's what they do."

I'm curious as to how the formidable Lord Sugar, who has amassed over five million followers on Twitter, and more than 17,000 on Instagram, deals with being in the public eye himself. And not for the first time, I'm surprised by an answer he gives. "I'm very conscious of putting out things that are politically correct. If I've got to say something strongly, I will, but I'm very conscious of what I put out."

Don't think for one minute though that Lord Sugar holds back on his opinions in real life. Earlier this year, the BBC's annual report disclosed salaries for staff earning more than £150,000 and the list of 96 talent featured showed that its top-earning male personality was paid at least four times as much as its highest-paid female. I broach the topic. "I don't think transparency over pay is the correct thing, it's a private issue and I think it's disgraceful actually that the BBC were forced to publish what people were earning," he says bluntly.

He also shares strong views when it comes to how the pay gap can be narrowed. "It can be narrowed by the lady herself saying, 'No, I want more money'," he says.

And finally, does he ever worry about the way he comes across to viewers as The Apprentice boss?

"It doesn't worry me," he affirms. "It worries some of my family... There's 140 hours of programming, some of it's quite fun. You see the funny side of things, the softer side of me in the boardroom. But that doesn't put bums on seats as far as the TV producers are concerned."

*The Apprentice is on BBC One on Wednesdays.