Detectives are also using secret surveillance cameras to track criminals suspected of the watch snatches. Since the beginning of the year more than 160 high-value watches, some worth tens of thousands of pounds, have been ripped from victims' wrists in the Central London area.
Celebrity victims in the so-called "Who's Who" robberies, involving jewellery and watches, include Britt Ekland, the actress, the Formula One boss Bernie Ecclestone and Anton Mosimann, the chef.
The watch thefts account for only 5 per cent of all street crime in Central London, the high-profile victims and the use of knives in several assaults has caused growing concern.
To catch the attackers, Scotland Yard is using men and women decoys, kitted out with expensive-looking watches and jewellery, to wander around high-risk areas as bait. The covert operation has proved successful in catching a number of prolific criminals.
Police believe there is a hard core of repeat robbers but that most attacks are opportunistic and there is no single group or gang. They have filmed key suspects trailing potential targets and in some cases videoed them bending over to make sure the watch is genuine.
The operation is part of a fresh drive against all street crime in Central London. In the past three months, street offences have risen by 16 per cent to 1,535 compared with the similar period last year.
Deputy assistant commissioner Andy Trotter, head of crime in Central London said: "The [criminals] are opportunistic thieves, they are disorganised and they will look around for likely targets. We see them wandering around, looking for targets, losing targets and finding another."
He said that most of the robbers were aged from 18 to 25 and travelled into the centre of the city from the north-west and south of London. A thriving black market for high value stolen watches operated in the capital. "They are very marketable," he explained. The so-called "time bandits" tend to work more in the summer when people are wearing short-sleeved clothes.
In the most recent celebrity mugging, Anton Mosimann, the chef, and his wife Kathrin were robbed at knifepoint outside their home in Kensington, west London on 5 July.
Mr Mosimann, 52, was punched in the face by the lone mugger, who forced Mrs Mosimann to hand over her pounds 10,000 Rolex. Mr Mosimann, former head chef at the Dorchester, also had his wallet taken. The couple had been returning home at night.
At the beginning of the month, a woman with her three-year-old daughter had her pounds 25,000 Jaeger Le Coultre watch torn from her wrist in north London by a man who escaped into a waiting car.
Last month, Robert Robinson, 71, the television and radio presenter and his wife Josephine were robbed of jewellery worth pounds 2,000 by three men.
In May, the wife of motor racing boss Sir Frank Williams lost up to pounds 100,000 in jewellery and a top-of-the-range BMW after being mugged at knifepoint outside her apartment by two men. In July 1996, another Formula One chief, Bernie Ecclestone, and his wife Slavica were attacked. Two thugs punched and kicked Mr Ecclestone in the face before wrenching a diamond ring worth hundreds of thousands of pounds from his wife's finger.
Multimillionaire financier Christopher Moran and his wife Helen were attacked in the same area. A watch and handbag worth pounds 15,000 were stolen. Muggers also snatched jewellery worth pounds 110,000 from Lady Weidenfeld, the wife of the publishing magnate.
Other celebrity mugging victims in the area have included media tycoon Michael Green and his wife, and actress Britt Ekland.
Earlier this year Miss Ekland told how she was left bleeding at a supermarket in Chelsea after a robber ripped off her pounds 10,000 diamond watch.Reuse content