A Somalian bus driver took up to 200 driving tests on behalf of fellow immigrants and charged them up to ?500 a time.
Deeg Mohammed, 27, impersonated hundreds of would-be candidates at a series of exam centres in a nationwide scam netting more than ?100,000.
Mohammed assumed the identities of his paying customers before passing the compulsory theory test with flying colours.
The father-of-one was only caught when suspicious officials noticed that a number of bookings were being made using the same credit cards.
After reviewing hours of CCTV footage they eventually found Mohammed sitting fifteen tests in six different counties.
Mohammed, who used his experience as a bus driver to pass, told detectives he felt honour-bound to sit the computerised tests for dozens of fellow Somalis as it was not available in their native language and they could hardly speak any English.
He was sentenced to 12 months in prison after admitting 15 counts of conspiracy to obtain property by deception at Guildford Crown Court.
He could have been jailed for a maximum of 10 years.
The court heard how he targeted exam centres in Southwark, Southgate, Harlow, Reading, Ilford, Luton, Croydon and Northampton between January 2004 and November 2005.
After successfully taking the exam he would send the theory certificate to his clients through the post so that they could then apply for the practical part of their driving test.
Mohammed, of Battersea, South London - who worked as a bus driver in the capital while also studying for a computing degree - was arrested at the end of last year after taking a test in Staines, Middlesex.
It followed an investigation by the DVLA and Driving Standards Agency into allegations that scores of exams were being booked using the same credit cards.
Matthew Banham, prosecuting, told the court that Mohammed was finally exposed as the imposter after a review of CCTV footage at all the test centres where the credit cards had been used.
'Mr Mohammed didn't appreciate the implications to the public safety'
The true candidates were then arrested by police as they arrived to take their practical tests and given cautions. Many confessed they had paid Mohammed between ?300 to ?500 to take the theory test for them.
Further investigations revealed that Mohammed and another man, Abdulliah Omar, had used credit cards to book over 200 tests. Police are still hunting Omar for his part in the fraud.
Richard Job, defending Mohammed, said he had come to the UK in 2002 and married an English woman of Somali descent who recently gave birth to their first child.
He said the defendant had lived in Northampton and Leicester before moving to London where he was coming to the end of a computer studies degree at Westminster University.
"These are offences without a direct victim," he said. "Mr Mohammed didn't appreciate the implications to the public safety and insurance companies of his actions."
The theory tests, he said, were available to applicants in a number of languages but crucially not Somali. As Mohammed spoke good English he decided to take the tests on their behalf out of "loyalty to the Somali community".
"Mr. Mohammed doesn't accept that he received any payment for his involvement in these offences but did it as a favour to those in the Somali community who do not have his command of the English language," Mr Job added.
"However I would accept that it is unlikely he would have done this without any financial incentives."
Jailing him Recorder Paul Clements said: "Ignorance of the law is not a defence and it stretches the imagination that anyone can pretend on 15 occasions to be someone else and not think they are committing a crime.
"These offences let loose onto the roads people who are not skilled to drive and people who are not skilled to drive can have accidents and hurt or kill others.
"A message has to go out from this court that judges do consider this a serious crime that merits a prison sentence and that is what you are going to get."
The DSA welcomed the sentence and said that it would actively seek to prosecute anyone trying to impersonate others to help them pass their theory or driving test.
A spokeswoman added: "It is a reflection of the serious road safety implications for the public that the judge in this case has seen fit to impose a term of imprisonment