Drivers of black cabs from Wandsworth and Wimbledon have joined hundreds of others to protest over the numbers of new cabbies flooding the suburbs.

The demonstration outside GLA headquarters, in Marsham Street, SW1, early on Tuesday morning, ended with a plea to Mayor of London, Ken Livingstone, for a survey of black cab demand in outer London.

Drivers say the results will prove that the ever-increasing number of suburban badges issued by the Public Carriage Office are swelling the ranks to bursting point.

Trainee drivers can study the knowledge' over five years for a green badge, or opt for the three-year study of one of 12 areas in outer London for a suburban badge.

But the time factor has become an increasingly crucial factor in prompting trainees to opt for the suburban, option, according to Wimbledon cabbie Andy Dunne.

He claims it has got easier for drivers to pass the suburban badge exam and says 28 new drivers joined the Wimbledon rank in the last fortnight..

"Before that you'd only get 28 in a year," he added.

Mr Dunne also claims the recent 50 per cent hike in fares after 8pm, will put some drivers out of work in the New Year - particularly if there is not enough work to go round.

Driver Graham Thomas, who picks up fares outside Sainsbury's, in Garratt Lane, said the problem with too many drivers has steadily worsened in his 12 years behind the wheel in Wandsworth and Merton.

He said one solution might be to enlarge suburban patches - to enable Wimbledon and Wandsworth drivers to pick up passengers in inner London' Putney and Clapham, for example.

Licenced Taxi Drivers' Association executive officer John Thomas told the press the demonstration had been peaceful and successful, with at least 400 drivers from outer London joining in.

It had made the point that "issuing licences without regard for the work that's available has got to stop" and a letter for the attention of the Mayor of London had been handed over to director of surface transport Peter Hendy.

A GLA spokesman said he med by the LTDA to have taken part in the demonstration. He was reticent about commenting further, but said: "We've got the letter and we are going to look into their points."