DANNY MARDELL is a man who likes a challenge. Whether boxing, cycling or mountaineering, not to mention a possible film role, the 39-year-old businessman is not one of life’s shrinking violets. His 20 years in business have seen him amass a fortune that he modestly describes as “adequate” but which he agrees is growing so exponentially that it may not be long before Mardell appears in The Sunday Times rich list.

Mardell is the managing director of Boss Group, a company based in Stratford, East London. Boss, which has 60 employees and turned over £20 million last year, has two core businesses. Boss Office Equipment is the largest dealer in the UK for Ricoh, the international office equipment suppler.

Boss Property Group buys and sells property in and around Stratford. If London’s dreams of hosting the 2012 Olympic Games become a reality, Boss is well placed to benefit.

Irrespective of speculation about where the Olympics will be held, Mardell recently told his staff that in the next financial year he wants them to make £100 million. “I don’t know how we’re going to do it but once I say we’re going to do it, we have to. That’s the way I operate.”

Mardell put his money where his mouth is recently when he announced that he was going to win the British white-collar boxing super-heavyweight title. Though he had been a champion middleweight in his youth for the RAF, by his own admission he was seriously overweight. Years of business lunches had taken their toll. But Mardell had a reason beyond extreme stress relief to venture into the boxing ring: his son Danny, now eight, was born with Down’s syndrome.

“I rejected him when he was born,” Mardell admits. “I’m ashamed to say it, but that’s the truth.”

For all that he had achieved in his life — the Bentley, the business empire, the mansion in Chingford, Essex — Mardell could not accept that his first son was less than perfect. But after nine difficult months there came a turning point.

“I realised that Dan needed me,” he says. “He’s a wonderful boy who never ceases to light up the room. I fell in love with him and wanted to do something to help him and other Down’s syndrome children.”

Mardell could simply have written a large cheque to charity but that is not his style. He attended a white-collar boxing event and resolved there and then to win a British title.

He was nearly 20 stone. He called the project “Danny’s Challenge” and set about raising as much sponsorship money as he could for Mencap, enlisting the help of “the Dark Destroyer”, the former world middleweight champion Nigel Benn.

The pair had been contemporaries at school in Ilford, Essex, but theirs was a relationship marked by feuding rather than friendship. They finally buried the hatchet after four or five “serious scraps”, according to Mardell, who subsequently followed Benn’s boxing career closely.

On the night the gruelling training with Benn paid off. Mardell, down to 15 stone, beat Alex Leitch, a lawyer with the legal firm SJ Berwin, and won the title. He also raised more than £100,000 for Danny’s Challenge. Many would have called time on the boxing but Mardell keeps climbing back into the ring, and has raised well over £200,000.

He has no plans to abandon his challenges — there is talk of a bout in New York in October, when Mardell and other white-collar boxers will fight the finest of their peers across the Atlantic.

Mardell is also participating in a 250km cycle ride around Moscow this weekend. The focus is on Russian children who have Down’s syndrome, with Mardell hoping to raise £10,000 for Downside Up. He feels confident that the ride will not be too taxing and he looks in such good shape it is hard not to agree with him.

He looks, indeed, fit enough to climb a mountain, and confesses that lurking in the back of his mind is an ambition to climb Everest.

“I’d better not say I’m going to do it, otherwise I’ll have to. Not yet, anyway,” he says.

Mardell’s formidable frame and granite jaw may also be on celluloid before too long: he has been approached to play Lenny McLean in a film of the notorious East End hard man and bare-knuckle boxer, who himself made a cameo appearance as Barrie the Baptist in Lock, Stock and Two Smoking Barrels before his death in 1998.