Tory leader David Cameron has bicycle stolen for a second time

The Tory leader saw his silver and black Scott bike chained to railings at 7.10am but an hour later it was gone, a spokeswoman said.

Mr Cameron borrowed another bicycle from Desmond Swayne, his parliamentary aide, and cycled to Westminster as usual.

He last lost his bike when it was taken from outside a supermarket near his home last summer.

He was later reunited with what he called the "priceless" two-wheeler after it was tracked down by a Sunday newspaper.

Mr Swayne and Mr Cameron usually ride to the Commons together on a Wednesday ahead of Prime Minister's Questions.

But on discovering his leader's predicament, Mr Swayne gave up his own bike to make sure Mr Cameron arrived on time for his pre-PMQs briefing.

Mr Swayne said: "His need was greater; the party would have expected nothing less.

"My only fear was that I had lent him a death trap and I might be held responsible for the by-election."

The MP for New Forest West, a Territorial Army officer, ran to the Commons instead.

On being reunited with his bicycle after the last theft, Mr Cameron said: "It's priceless to me. I've done over a thousand miles on it and three sponsored bike rides of 250 miles each so it's like an old friend."

On that occasion thieves simply lifted the bike over the three-foot bollard on Portobello Road Mr Cameron had chained it to while he shopped for food on his way home.

Mr Cameron's cycling habits have caused him embarrassment in the past.

Last year he was criticised by road safety charities and forced into an apology after being photographed riding the wrong way down one-way street, going the wrong way around a keep left bollard and riding across a crossing for cyclists and pedestrians while the signal was red.

Previously it was revealed that he was followed on his "green-friendly" ride to work by a chauffeur-driven car carrying his briefcase, documents and shoes - a practice he has now stopped.