Mr Cameron is a keen cyclist
David Cameron's bicycle has been stolen for the second time in the past year.
The silver and black Scott bike - which he has likened to an "old friend" - was chained to railings near his home at 0710 BST but an hour later it was gone.
The Conservative leader borrowed a bike from his Parliamentary aide to get to prime minister's questions.
In July 2008 his bike was stolen from outside a Tesco store near his west London home but was later found in a nearby side street.
A Sunday newspaper helped Mr Cameron to recover the bike a few days later. Mr Cameron has described his bicycle as "priceless" after completing three sponsored rides of 250 miles each on board.
The latest theft has been reported to the police.
'His need greater'
However, he was still able to cycle to Parliament after Desmond Swayne, MP for New Forest West, offered him his bike.
The two normally cycle together to Parliament on Wednesdays but, on this occasion, Mr Swayne decided to jog there.
"His need was greater," Mr Swayne said of Mr Cameron's predicament and his gesture in lending his bike.
"The party would have expected nothing less."
The Conservative leader's cycling habits have caused him some political discomfort in the past.
While regularly cycling to Parliament, it emerged that a chauffeur-driven car followed behind Mr Cameron carrying his briefcase and documents - an arrangement he has since ended.
More than 100,000 bikes are reported stolen every year although the actual figure is thought to be much higher.