(KIRSTY WIGGLESWORTH ~ Associated Press)
"I feel very strongly about this. We won't let it erode away our reputation," said Catherine Michael, 51, showing her green badge that allows cabbies to work as licensed drivers. "We want to stay the best in the world."
Long lines of protesting taxi drivers, estimated by police to reach 1.5 miles, surrounded the Public Carriage Office -- which is responsible for administering the taxi test -- in north London.
The man, who cannot be named for legal reasons, was found guilty in 2001 and has applied to take a test called "The Knowledge" -- which all London cabbies must pass to drive a black taxi.
The 38-year-old, diagnosed as a paranoid schizophrenic at the time of his trial, was released in 2005 and is no longer on parole.
Jim Kelly of the Unite union said that allowing the man to become a cab driver could damage London's reputation for having the safest taxis in the world.
"We feel the traveling public would be at risk," he said.
Black taxis are considered one of the safest forms of transport by Londoners trying to get home after a night out.
But their reputation was dented earlier this year when one driver was found guilty of raping or sexually assaulting several female passengers after drugging them in his cab. John Worboys, 51, was convicted in March of 12 attacks, but dozens of other victims came forward in April to say they, too, had been attacked.
Transport for London officials said there were no grounds to refuse the new application as the man had served his time for manslaughter and passed background and medical checks. It said an independent committee is reviewing the case before a final decision is reached.
"The issue uppermost in our minds is the safety of passengers -- nothing more, nothing less," said a spokesman for the transport body who asked not to be named because of departmental policy. "That's why there is an urgent independent review of the facts."
But this has not appeased cab drivers who dismiss the decision to let the man take the test as being too politically correct.
"Everyone is given an equal chance but the cabs' reputation will go down the toilet. We're not prepared to lose it, no way," said Grant Davis, chairman of the London Cab Drivers' Club union.
"I keep asking, would you like to be the woman at the back of this guy's taxi the day he forgets to take his medication?"