Strolling along Upper Richmond Road in the west London suburb of Putney last Wednesday, Luke Johnson had not chosen the ideal evening to launch the 23rd outlet in his Strada chain of pizza restaurants.

But the Channel 4 chairman and co-founder of Risk Capital Partners, the private-equity firm, was unperturbed at spending his 43rd birthday working.

For Johnson, who began his business career running discos as a student at Oxford before making a fortune from the flotation of Pizza Express, last Wednesday was just one more day’s graft in his quest to benefit from Britain’s booming leisure industry.

Few would bet against Johnson making another tidy sum from his latest restaurant venture. But the man himself believes that the opportunities to generate serious wealth in the future lie far from the cut-throat world of London’s dining-out market or its cacophonous media hub. If he were doing it all over again, Johnson would look much further afield, at emerging markets such as Brazil, Russia, India and China.

“If I were starting out today, knowing what I do, I would learn the language in one of those countries and invest in a natural-resources business like mining,” he said. “Markets like Britain’s, with their mature economies, are not the real growth engines of the future.”

What’s more, Johnson also believes there has never been a better time to be an entrepreneur: “There are more people, more opportunities, more funding and more angel investors here than ever before. Certainly, there is more competition for deals, but anyone who believes there has been a better time to be an entrepreneur is looking at the past through rose-tinted spectacles.”

TODAY’s business leaders may have few regrets, but the opportunities and market shifts that have opened up in recent years have prompted many of them to ponder the great “what ifs”. The Sunday Times surveyed 30 of Britain’s leading businessmen and entrepreneurs to establish what they would be doing if they were starting all over again. “What would you be doing if you were 25 years old?” was the question we asked. Their answers may surprise you — and provide food for thought.

Some were content with their lot, suggesting that, given the chance to start over, they would still stick to the sectors they are in. Perhaps those remarks come partly from a desire not to antagonise their shareholders, but they also reveal a depth of passion in today’s crop of entrepreneurs and business leaders about what they do.

Nevertheless, most said that given the opportunity to start again, things could be a whole lot different.

Greg Hutchings, executive chairman of Lupus Capital but better known as the architect of the old-style conglomerate Tomkins, thinks starting out today throws open a whole new set of possibilities: “Someone new should do something in handling money. There has been a huge growth in money management, and that runs from hedge funds and fund management to investment vehicles and private equity. There is so much money around these days that it needs running and managing.”

Stelios Haji-Ioannou, founder of Easyjet, the budget airline, has been amazed at the valuations placed on online travel companies at the expense of traditional businesses such as his. He would definitely try something different if he started again tomorrow. “The people who own the planes and hotels and cars are valued at a fraction of the people who sell hotel rooms and car rental and plane tickets. Easyjet was a big success but I wish I had started Expedia,” he said.

And even the lucrative world of private equity has those who think the party might be somewhere else in years to come.

Sir Ronald Cohen, founder of Apax Partners, said: “You have to look at technology. The room for growth there is just extraordinary. Exciting things have happened already, but it really is just beginning.”