A "gaping" legal loophole allowing anyone to clone a number plate is today exposed by a Yorkshire MP – who bought an exact replica of the one on Gordon Brown's own car to prove it.   Conservative Shadow Roads Minister Robert Goodwill, MP for Scarborough and Whitby, used nothing more than the registration number on the Prime Minister's Jaguar, website Google, and a credit card to purchase a made-to-order copy from a UK company – without breaking the law.

He hopes Mr Brown will now take notice of a problem with grave implications for terrorism, fraud and serious crime. The Yorkshire Post is not revealing the number plate for security reasons.

The Department for Transport insisted last night that recent changes to the law meant there were now considerable safeguards to prevent cloning.

It pointed out that motorists had to show proof of ownership and photo identification when buying a new number plate for use on the public highway, and that suppliers had to be registered and keep scrupulous records of sales, which can be checked by the police and Driver and Vehicle Licensing Agency (DVLA).

But Mr Goodwill has found that no such checks are demanded from the manufacturers of so-called "showplates". These are plates carrying words, letters or numbers dictated by a customer online or over the phone, which are theoretically only used off-road, at events like motor shows or in car showrooms.

But police chiefs say there is absolutely no difference in size, materials or lettering between genuine registration plates and most showplates.

The Association of Chief Police Officers (Acpo) said last night that fake registration plates from showplate suppliers are being widely used to disguise the true origin of some of the estimated 25,000 cars cloned each year.

Mr Goodwill, a former member of the Commons transport select committee, acknowledged that the Government had made "sensible moves" recently to tighten up the regulation of number plate suppliers, but that it was now time to investigate online showplate shops.

"You can drive a coach and horses through the loophole, which is someone saying they want to buy a plate for 'show purposes' instead of a registration plate," he said.

"It took me literally 10 minutes to order the clone plate. As the Prime Minister's Jaguar arrived off Parliament Square I jotted down the number, which any member of the public could do, went back to my office, Googled the word 'showplate', and found a host of UK companies offering made-to-order plates, no questions asked.

"I typed in the number I wanted to clone, paid my £20 and two days later they arrived in the post. And they were exactly the same as those on my car."

Last night Supt John Wake, of Acpo's vehicle crime intelligence service, compared the size of the legal loophole in question to the Grand Canyon.

"The loophole is gaping, embarrassing and frankly crazy," he told the Yorkshire Post.

"There's absolutely no doubt that many showplates are being used for cloning.

"The fact is that the number plate is the only part of a 21st century car that has not changed a bit since the 1930s. It's still just a block of plastic or metal. I no longer have any faith in the number plate."

Supt Wake admitted it was "really difficult" to calculate how many cars were being cloned, and for how long, but he said the police's working "guesstimate" was that it was about 25,000 each year – a quarter of the cars stolen every year which are never seen again by their rightful owners. Yorkshire Post 30 August 2007