Transport Secretary Heidi Alexander has vowed to end a “black market” in driving tests which means motorists are paying £300 for the chance to lose their L-plates - but admitted the Government is to miss its target by eight months. A shortage of examiners means motorists have to wait months to book a driving test, which usually cost £62. But a thriving underground market has developed in which profiteers arrange tests on the official computer system and then sell the appointment at an inflated price.

The Driver and Vehicle Standards Agency (DVSA) has a target of cutting waiting times to seven weeks by the end of this year but Ms Alexander told MPs she didn’t expect this to happen until next summer. She said: “The waiting times that people are experiencing are totally unacceptable.”

Speaking to the Commons Transport Committee, Ms Alexander said the DVSA has been instructed to make “additional overtime incentive payments to everyone delivering extra driving tests”.

She also said the Government will launch a consultation next month on changes to the driving test booking system, in an attempt to stop bots mass-booking new slots and reselling them on the black market for inflated prices.

The DVSA has been looking for ways to improve its website so that appointments cannot be snapped up by automated systems or “bots” used by people planning to sell the slot on.

Instructors have also warned that the shortage of tests means learner drivers are taking them before they are ready, because once a driver has managed to book an appointment they are unwilling to give it up and risk another long wait.

Trade body the Driving Instructors Association has warned that trainee drivers are more likely to “have a go” at a test if they have a slot booked, even if they are not test ready, rather than lose the opportunity and have to go back into the system and wait months for another change.

Recent analysis by the AA Driving School showed the average waiting time to book a practical test in Britain was 20 weeks in February, up from 14 weeks a year earlier.

The number of test centres with a 24-week waiting time nearly doubled over the period, from 94 to 183.

Steve Gooding, director of motoring research charity the RAC Foundation, said: “The current system is failing learner drivers even before they sit their tests, and today’s news shows there won’t be a quick fix to the frustratingly long waiting times.

“For now, the best way candidates can help themselves is to be as prepared as possible for test day when it does eventually arrive so they have the greatest chance of passing.

“At the moment less than 50% of tests taken are passed.”