Nurse Susan Usher is leaving her job at Moorfields Eye Hospital because of the cost of the charge. Unison, the heath service union said it feared there would be many more cases in central London. The union is urging Ken Livingstone to postpone the charges so the consequences for public sector workers can be assessed.

Congestion in London is soaring and will become much worse even though traffic levels have fallen states the recent study for business campaign group London First.

It blames muddled management of the road network and identifies the belief that the "numerous traffic-management ideas and fundamental changes to the traffic-signalling arrangements in the run-up to congestion charging are causing these difficulties."

The study by consultants Steer Davies Gleave says peak-time traffic levels are similar to those in the early seventies but they have fallen since the nineties by five percent.

Motorists paying the £5 congestion charge will be refused a refund if their plans change and they do not enter the zone.

Only drivers paying for a month in advance can get a refund but they must also pay a £10 "administration charge".