Sir Richard Branson has his legs slung across the table between us. He did take the precaution of asking whether I minded him resting them there. He is after all a busy man who spends much of his time flying from country to country trying to make the world a better place.

His philanthropy, though, wasn’t enough to immunise him against a headline earlier this month which read: “Goodbye, Britain: I’m a tax exile.”

When I ask whether he now sees himself as a citizen of Britain or a man of the world, Sir Richard says it’s the latter. “I’ve always felt that the world should be one world, we shouldn’t have borders. [We] spend a lot of our time on conflict resolution issues. There shouldn’t be conflicts, it sounds like a naive thing to say.”

Sir Richard is in London to celebrate 40 years of Virgin Records, the company he sold, amid tears, in 1992 to help fund his airline business. He’s also in the UK to promote a start-up scheme for entrepreneurs.

I wonder whether Sir Richard misses Britain, given that he lives on his very own island in the Caribbean. “Do I miss it? I just love the British Virgin Islands. When I’m there I’m active till nine at night – it doesn’t get dark till then – and here I know I’d be watching some television in the evenings in winter. You know, it’s just a different way of life.”

It’s this way of life that provides part of Sir Richard’s defence against the accusation that he fled the country for tax reasons. He argues that the coverage has been “very misleading”.

Armed with a Diet Coke, he says: “I’ve desperately wanted to go and live in Necker for many years. I waited until I got into my 60s and have just decided that it’s more likely that I will be a more useful member of society until I’m in my 90s by living and working in the most beautiful place in the world.”

Sir Richard argues that if he’d wanted to avoid tax he would have worked full time from the island when he bought it aged 28. He maintains that from an income point of view it makes no difference whether he lives in Britain or on Necker.

“My income from speeches is about £6m-£8m, 100pc of which I give to charity, so whether I lived [in Britain or elsewhere] it would be tax-free anyway.

“And then I make a smallish salary, which I give to charity as well. I work bloody hard. I travel the world for six months of the year working my balls off, it’s pretty well all not for profit.

“I’ve made enormous amounts of money while I’ve lived in England [which has all been taxed and] which I can live off for the rest of my life and my children could live off for the rest of their lives.”

The negative press surely must have hurt. “I think I’ve got a thick skin over the years and we’ve got 11 or 12 million followers on our social media and the great thing about that is I can respond.

“In the past, once a newspaper had written something and you felt it wasn’t written in the way you’d like it, maybe you could write a little letter in to correct the impression. Now we can actually reach millions of people and put things right very quickly and looking at the feedback from the public, most people I think know what the situation is.”

Of course, Sir Richard cashed in on being a popular, patriotic British entrepreneur and taking on the bigger guy – often British Airways. Does he feel like he’s public property?

“Yes, I think that’s fair comment and reputation’s important so you’ve got to fight to defend [it] on occasions. And you’ve got to do your best not to let people down.”

There are a lot of people not to let down. After our interview he’s off to meet the President of Kenya, who wants to thank him for his support in the aftermath of the recent terrorist atrocity.

“We’ll be talking about the fact the British Government has warned people not to come to Kenya because of the horrible thing that took place in the mall there. I tweeted and blogged that I thought it was wrong of them to do that and it was wrong when they did it with Bali.

“You don’t do it when America has a 9/11 attack, we wouldn’t expect Kenyans to do it to us when we have a bus blowing up in our streets.”

Virgin Atlantic, he says, doesn’t fly to Kenya, so he wasn’t motivated by business interests. From Kenya, Sir Richard will move on to Cape Town for a meeting with The Elders, a group of international global leaders he set up to work for peace and human rights.

Although Sir Richard operates on the international stage, the interests of Britain in the global economy are still important to him. Leaving the European Union would, he says, be madness and he’s opposed to the promise of an in/out referendum in 2017.

“We’ve already made up our mind to be part of Europe,” Sir Richard says. “It’s ridiculous to have to go through a whole process again, [an] unsettled process. Our European partners are pretty exasperated with Britain anyway. I can see why, politically, David Cameron had to do what he did, but we made a decision years ago.

“We should just get on with it, stick with the decision and not dither.”

There is also, he adds, always the danger the referendum could go, as he puts it, against Britain, which would be devastating for the economy. It would make very little difference to Virgin, he says, because it’s a global brand. “But there’s a lot of Britain’s companies it would do enormous damage [to] and therefore to jobs and I think it would set Britain back enormously.”

As he’s admitted before, Sir Richard says he once tried not to pay the 35pc export tax on records shipped to France or Belgium and that it was a mistake. At the time – in his early 20s – he spent the night in a cell on a bare, plastic mattress with an old blanket before later negotiating an out-of-court settlement with Customs and Excise.

Now, he thinks it would be a disaster for this country suddenly to have to start paying tax for exporting goods into Europe and for Brits not to be able to live in Spain and Italy or work in France and Germany.

But above all he sees the EU as a deterrent to conflict. “My generation is the first that hasn’t been to war in Europe and people forget that.

“We’re never going to go to war with each other as part of a European Union where people get married together, where people can live and work in each other’s countries. There’s always little niggles, there are going to be laws that people are not going to like, but Britain should be part of trying to improve [these].”

The other major issue on Sir Richard’s radar is, unsurprisingly, aviation. And on this issue he is heartily sick and tired.

“There hasn’t been another runway [at Heathrow] since 1945 or 1946 and Great Britain has been held back as a result,” he says.

Never mind a third runway, Sir Richard thinks there should be a fourth one, too. This summer Gatwick announced its preferred location for a second runway of its own, but Sir Richard wants more – “Two [new ones] if we’re going to compete with Europe generally,” he argues.

Due to the capping of Virgin Atlantic’s runway slots at an overcrowded Heathrow, Sir Richard says the company has ground to a halt in the UK.

“It doesn’t matter to Virgin at all, because the moment we capped out in the UK we went to Australia, we went to America, we went to places which welcomed us. But it’s sad for Great Britain that that investment is not taking place and the damage that’s been done to the UK is massive. China – all those planes are pouring into Europe, they’re not coming to the UK.

“We haven’t been able to launch any services into South America because we don’t have the slots.”

He blames the Government, this one and previous ones. “We need all parties to be brave and do what’s right for Great Britain and not what’s right for short-term political expedience,” he says.

When we move on from planes to trains, Sir Richard says he’s broadly in favour of the High Speed 2 rail plan that it is claimed would cut journey times significantly between London and cities further north.

But he urges the Government to consult more widely with the industry. “I think there’s a danger that you shouldn’t have engineers be the lead planner in a scheme like this without a lot of commercial input to make sure that it works,” he says.

Whatever happens, Sir Richard argues, there have to be incremental improvements on the West and East Coast lines.

Despite his fears about runways and the EU referendum, Sir Richard says he’s optimistic about the British economy.

“Not just about Britain, I think America, Britain, Europe generally are turning the corner.”

When I ask whether he thinks it’s a good time to be starting up a business in the UK, he says any time’s a good time to do it –and not just in the UK but anywhere in the world.

Earlier in the day, Sir Richard helped to spearhead Virgin’s collaboration in a Government-backed scheme to provide loans and mentoring to entrepreneurs who choose launching a start-up over university.

“Even if you don’t succeed, you’re going to learn a lot more by setting up a business and trying to make it a success most likely than going to university to study about setting up a business and making it a success,” Sir Richard says.

“It’s fantastic that the Government has embraced it and I think this will make a massive difference in the UK in the years to come.”

Sir Richard, famously, never went to university. If a young Sir Richard were starting a business today, what would it be focused on? “Energy is what makes the world go round and therefore clean energy is what makes the world go round in a clean way and I would certainly look at clean energy – something that Virgin does anyway.

“This building here [where the interview is taking place in London] I’m sure could save 50pc of its energy bill. I might come and do this building and offer to save 50pc of the energy bill if they’d like to give me 50pc of the savings.”

A greener future is something that preoccupies Sir Richard. He’s excited about a company that is re-funnelling the soot from aluminium or steel plants and turning it into jet aviation fuel.

Virgin Atlantic, he says, has first option to use the fuel when there’s enough of it. “[It’s] recycling at its very best: it’s basically taking the s**t that would otherwise be up in the earth’s atmosphere and using it again.”

Sir Richard thinks green air travel will definitely happen. “The other exciting thing is the way that batteries are becoming more and more efficient and I think one day we’ll have planes powered by [them].” He says that his space programme, Virgin Galactic, will be a very environmentally friendly way of getting around the world.

“We’re going to run out of fuel one day so we might as well start moving to a world which is powered by solar, by wind, by clean forms of energy,” he says.

Sir Richard is trying to speed the process up and has set up a “carbon war room” with the aim of balancing the earth’s carbon books by removing tonnes of the element from the atmosphere without damaging industries or countries.

Climate Armageddon is definitely avoidable, Sir Richard believes, although he adds that it would help enormously if governments also played their part by getting rid of all subsidies of non-green fuels.

Sir Richard Branson is a man of contrasts. He’s an unlikely looking knight, with his black leather jacket and trademark long, golden hair and beard. For a man drawn to the thrill of altitude-defying challenges – such as attempting to fly around the world in a hot-air balloon – he’s very down to earth.

For a brilliant self-publicist, he can come across as almost endearingly shy. For a billionaire who lives on a paradise island, he is in some ways remarkably un-showy (“I wouldn’t feel comfortable getting out of a flash car”).

And for a deep thinker who champions conflict resolution, he also has “enormous fun”. As he says himself, he’s been involved in so many different areas that he knows something about most things. Even tax.

Photo Credit: Sir Richard Branson, Founder of Virgin Group, arrives at a seminar about the Virgin StartUp scheme for young entrepreneurs at Box Park in east London. Olivia Harris / Reuters