A bit on the side: The celebs are fake but the cash is real for dead ringers

Have complete strangers ever whispered "Is that her?" as you walk by? If you've noticed that people regularly do double-takes as a result of your uncanny physical resemblance to a famous individual, you could make money just by turning up at events and looking like a star.

Caroline Bernstein is an actress by profession but is regularly in demand as a lookalike for celebrities including Cherie Blair and even Margaret Thatcher.

Sometimes, with wig and make-up on, she has genuinely been mistaken for the real thing. "I was doing a PR stunt in central London as Sharon Osbourne, with a lookalike who does Ozzie," she says, "and we stopped traffic. Everyone was taking our photographs and tourists were coming up to us in the street to talk to us. Another time I was being Cherie Blair with a Tony Blair lookalike at Alton Towers. We were there to launch a new ride. A woman came up to us with tears in her eyes thanking us for all we had done for the country. We didn't like to say we weren't real and that Tony and Cherie really wouldn't be likely to open a ride in a large northern funfair."

Among the most sought-after lookalikes for parties, public relations stunts and corporate hospitality events are people who resemble David and Victoria Beckham, while dead ringers for members of the royal family are still in vogue – in particular the Queen, princes William and Harry and, increasingly, Camilla.

Elsewhere, you'll get plenty of work if you look like film heroes such as the latest 007, Daniel Craig, or Harry Potter. "Marilyn Monroe lookalikes are enduringly popular," says Ms Bernstein. "There are two or three who are incredibly in demand. They have that aura around them – almost like the real thing."

You could also do well if you resemble a TV character such as Del Boy from Fools and Horses or David Brent from The Office. Even Big Brother contestants have their own market. "I used to work with Chantelle Houghton," says Ms Bernstein. "She was a fantastic lookalike for Paris Hilton. As soon as she won Big Brother, though, the look-alike agencies were inundated with girls saying they could 'do a Chantelle'."

With PR firms increasingly aware of the pulling power of fake celebs, a good lookalike can earn between £350and £800 for a job, with the fee running into thousands for a foreign commercial. Most jobs are in the evenings – corporate events, birthday parties, wedding receptions – but you could be booked to help launch a new product at an exhibition or take part in a PR stunt out on the streets.

This kind of work comes through specialist agencies, so you need to be on the books of at least one of them. Susan Scott Lookalikes (www.lookalikes-susanscott.co.uk), Splitting Images ( www.splitting-images.com) and Fake Faces ( www.fakefaces.co.uk) are some of the biggest agencies in the field. Before accepting you on their books they need to see a photograph, ideally in colour, resembling the famous person you represent.

It's a good idea to invest in wigs, clothes and accessories that make you look more like the personality and to study videos of their speech, their gait and their mannerisms.