The biggest problem with seat belts in cabs is that people don't put them on

Bob Oddy Licensed Taxi Drivers Association

Working Lunch discovered that a sharp tug by a previous passenger, or the juddering of the taxi, can make the safety belt jam.

Subsequent passengers then cannot release the belt to put it on.

Mary Williams, executive director of road safety organisation Brake said it was an "absolute disgrace" that some seat belts in taxis were jamming.

"It's an equal disgrace that in other taxis, particularly minicabs, you sometimes can't even get to the seat belt because it is stuck behind the back of the chair - it is effectively in the boot.

'Endangering lives'

"If you can't belt up, you are endangering your own life and the person in the seat in front."

She said Brake would be raising the matter with the government and working with taxi drivers to encourage them to consider seat belt safety.

Peter Longland, a senior manager and seat belt designer with Autoliv, said the problems were intrinsic to the design of the seat belt retractor.

"A lot of older black cabs were designed quite a long time ago and the rear installations weren't really designed specifically for seat belts to be fitted."

Annual safety test

He said it was unlikely to be a widespread problem across all black cabs, but was most likely to effect London's taxis.

But a spokeswoman for the PCO said it "categorically refutes" the suggestion that lives are put at risk by faulty seat belts in the capital's black cabs.

"Every black cab in London is subject to an annual inspection," she said.

"The operation of seat belts is tested at this inspection, and if a fault is found the vehicle licence is suspended, meaning it cannot be used on the road.

"The Public Carriage Office is aware that there was a problem some time ago with seat belts fitted to older cars. That problem has now been addressed."

Bob Oddy general manager of the Licensed Taxi Drivers Association, said that as well as the annual safety inspection by the PCO, spot checks were made throughout the year.

"The biggest problem with seat belts in cabs is that people don't put them on," he said.

"I don't know of any official survey, but I don't need one to tell me that 90% of people don't wear them."

His organisation represents 6,000 London black cab drivers.

The full report on seat belt safety will be broadcast by BBC Two's Working Lunch on 26 March at 1230 GMT.