The whole wheel collapsed and deflated, bringing me to an abrupt halt right in front of the camera! Anne Campbell MP

The 40 MPs and 10 Peers, including transport minister Dr Kim Howells, will be joined at the Tate Modern start by two British Special Olympic champions.

Organisers of Wednesday's annual event say they want to show that cycling is for everyone, whatever their ability.

National Cycle Week began on Saturday and continues until next Sunday.

The Parliamentary Cycling Group, which organised the event, is one of the largest cross-party groups with 90 members.

The MPs say they want to show cycling is for everyone

Anne Campbell, lifetime cyclist and Labour MP for Cambridge, admitted she was known locally as 'MP on a bike'.

"I was being filmed by the BBC in Cambridge, for a short piece about MPs using bicycles.

"The camera has just started rolling when the worst happened: not just a puncture, but the whole wheel collapsed and deflated, bringing me to an abrupt halt right in front of the camera!"

Lord Butler, former head of the civil service, explained how his bike use almost caused Margaret Thatcher to believe there was a constitutional crisis.

Thatcher's consternation

When the 1983 election was announced, he left 10 Downing Street and cycled to Buckingham Palace to convey the Prime Minister's arrangements to the Queen for her approval.

"All went well until on my return journey when I was prevented by the police from cycling across Horse Guards Parade because of a rehearsal for the Trooping of the Colour," he said.

"The delay caused consternation to Mrs Thatcher who thought that her plans must have run into some sort of difficulty."

The Liberal Democrat environment spokesman Norman Baker said: "When I was first elected, I paid an official visit to a County Council building for a function in Lewes, arriving as usual by bike.

"But I found there was nowhere to park it - as usual - so I wheeled it into the reception, hoping to leave it there.

"The receptionist looked at me aghast, telling me I couldn't possibly leave it there - and would I mind moving it very soon, because they were expecting the MP to arrive any second."

David McNay and Allan Walsh lead the Great Britain cycling team in the Special Olympics.

Mr McNay said: "It's a great opportunity to come down and ride with all these MPs.

"It will be a good experience to show them what we can do."