There is nothing new in the sight of undercover police officers dressed in leather jackets and trainers hanging around street corners trying to nonchalantly sniff their way into the underworld. It is a principle of nearly every British or American cop programme that the good guys look more like the bad guys than the bad guys themselves. Sometimes they can really be the bad guys too. Anti-corruption officers recently swooped on the east London offices of serious crime busters, the Flying Squad, after a detective charged with burglary and drug dealing accused dozens of officers of similar offences. The detective, charged with a GBP500,000 (HK$6.38 million) drug-trafficking offence, has implicated up to 30 colleagues in what could be the biggest police corruption scandal for 20 years. The allegations are so serious that the detective has even been moved to a safe house outside the Metropolitan Police area so angry colleagues cannot get at him. Perhaps he will end up in the latest guise of the undercover cop scene. Police in Brixton, the scene of rioting in the 1980s, a tough area of ethnic minorities and lots of street crime, have taken a lesson from Hollywood. The little old lady in head scarf, struggling along laden down with carrier bags, may be something quite different in reality. The police have taken to disguising undercover officers as pensioners and using professional make-up artists to transform them into a variety of characters who the police feel are at risk of being attacked. The technique is similar to that used in films such as The Nutty Professor when Hollywood star Eddie Murphy was turned into Sherman Klump, a 190-kilogram scientist. In the Brixton case, young undercover officers are aged dozens of years with the help of latex masks and make-up and transformed into apparently frail and vulnerable old ladies. The decoys are sent on patrol in crime hot spots where muggers are known to strike, although they are constantly surrounded with back-up from an undercover squad which is on hand to make arrests. Decoys have been used for a long time on the streets of London to trap muggers and 'Rolex robbers' - gangs who prey on the ostentatiously wealthy to steal their watches. But it is the first time that actual sophisticated make-up techniques have been used to catch muggers. The ruse has its own dangers though. In August a detective posing as a wealthy foreign visitor wearing a Rolex watch was stabbed when his back-up team failed to arrive in time. Inspector Brian Patrick of Brixton police commented: 'Our message to the robbers in Brixton is simple - be careful because you could be robbing a police officer with several colleagues waiting to make an arrest.' The decoys will not just be limited to old women - several types of vulnerable people will be created. 'The technique is very effective,' said Inspector Patrick. 'We can give people jowls and double chins using moulded latex to build up on the face and make them appear older.' The police have signed a deal with a professional make-up firm for some of the work and students from the Wimbledon School of Art have also been involved in making up undercover officers. The police deny they are actually entrapping potential criminals and they do not walk about with bank notes or wallets hanging out of their pockets. The tactic is finding success with several muggers arrested. Ironically the reality of street crime is that it is not just the old and frail who become mugging victims. A high proportion of robberies actually take place on young men in their 20s who are attacked late at night on their way to or from clubs.