If Alexis Alexander wins his High Court test case to open a loophole in traffic laws, drivers across the country 'caught' by no U-Turn signs could have millions in fixed penalty notices refunded.

Mr Alexander, a tennis coach from Caversham, Berks, says that a no U-turn sign has no legal power to prevent a driver carrying out a three-point-turn, as he did, and that motorists can lawfully get round the restriction in that way.

Alexis was hit with a £65 traffic fine in Fulham, which went up to £195, on Mother's Day in 2012. He is asking a top judge to rule that drivers cannot be fined for performing a prohibited U-turn so long as they put their car in reverse during part of the manoeuvre.

Mr Alexander said outside court: "I was delivering flowers on Mother's Day to the mother of my Godchildren. I had been doing the same manoeuvre for decades without being penalized, as had thousands of other people. I knew nothing about the subject but I've spent two years on it now and I could write a book on U-turns."

He won permission to seek judicial review on the point from a High Court judge last year, and lawyers for Hammersmith and Fulham Council, which issued the fine, admit that the traffic regulations definition of a U-turn 'does not describe the manoeuvre in detail.'

However they say that a 'broad' legal definition ought to be adopted, which allows local authorities to legally penalize motorists for three-point turns, or any other manoeuvre which involves an about-face, in areas where U-turns are banned.

Judge Andrew Keyser QC, who is scratching his head over the case at London's High Court, today warned that councils could face 'a very significant burden of repayment' if he finds in Mr Alexander's favor.

The court heard that Mr Alexander was delivering flowers to the mother of his Godchildren in West London in March 2012 when he was caught on CCTV performing a three-point turn on Gliddon Road North, Fulham, in order to avoid a no right turn sign.

When his challenge to the fine was rejected by the Parking and Traffic Appeals Service (PATAS) in December last year, he brought his fight to the High Court, winning permission to seek judicial review in July last year.

Celina Colquhoun, the council's barrister, said: "There exists no other road sign which could be used to prohibit a three-point turn - this strongly suggests that Parliament intended the U-shaped diagram on the sign to cover both. To conclude otherwise would in effect be to encourage drivers to carry out very dangerous turns...in order to avoid being "caught" by the aforementioned sign."

She told the judge that the council had been unable to find a clear definition of what a no U-turn sign prohibits.

Representing himself, Mr Alexander, a Lawn Tennis Association accredited coach and former taxi driver, told the judge he believes he is 'performing a public service' by carrying on his fight against the penalty charge.

The judge reserved his decision on the tricky case until a later date.