Simon started out in 1972 selling hand-knitted coats from a market stall just around the corner from where he stood.

Thirty-three years later he was back — for one day — selling Monsoon samples to raise money for the Monsoon Trust, a charity that provides education for children, young people and women in India and the Far East.

“Had a good year, Peter?” said “Honest Barry”, a long-standing Portobello Road trader. “Not bad,” he replied.

In fact, Simon has had a very good year. His family’s worth has almost doubled to more than £400m in the past 12 months. Monsoon’s share price has soared 107%. With 112m shares — a 62% stake — every penny on the share price adds £1m to the Simon fortune.

While high-street rivals struggle, Monsoon and Accessorize, another part of the group, are stealing market share. Last year Monsoon announced a 17% increase in sales to £271.4m and a 12% increase in pre-tax profits to £44.1m.

Being different has been the secret of the group’s success, said Simon.

“We don’t want to be like everyone else. A lot of effort goes into trying to keep it different. By and large I think we have succeeded,” said Simon in his first press interview for almost a decade.

Desperate to warm up, he popped into the Electric Cinema on Portobello Road for poached egg on toast.

The cinema, private club and restaurant is another Simon venture. He restored the cinema and converted an empty Indian supermarket and a derelict dairy next door. The complex is now run by Soho House.

Simon is passionate about the cinema and used the Electric when he was squatting around the corner. What was a sentimental investment is now one of London’s most fashionable clubs and a very profitable venture. “It’s typical of Peter,” said one adviser. “Whatever he touches turns to gold.”

More recent investments have included buying 8% of Gum, the Moscow department store, and a stake in Highland Gold, the Russian gold producer. He has also invested in a string of films.

Yet despite having made one of the biggest fortunes in retailing, Simon remains something of an outsider, shunning the gossipy “retail village” that is dominated by former Arcadia and Marks & Spencer directors.

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