As the former shadow home secretary officially tendered his resignation as an MP, Labour pronounced the resulting contest for his Haltemprice and Howden seat as "phoney".

His most likely opponents in the July 10 by-election now include a market trader from Northampton and The Mad Cow Girl - party secretary of the Monster Raving Loonies.

Liberal Democrat leader Nick Clegg announced last week he would not enter a candidate because he agreed with the principles behind the Tory's stand against 42-day pre-charge detention.

Despite Mr Davis's repeated attempts to goad Gordon Brown into entering a candidate for the by-election, Labour confirmed they would not, branding the by-election a waste of taxpayers' money.

Dianne Hayter, chairman of Labour's National Executive Committee, claimed Mr Davis had done a deal with Mr Clegg and never intended to put his seat at risk.

"The Labour Party is happy to spend every day until the next election debating with the Tory party on 42 days and whether it is right to use CCTV and DNA evidence against criminals," she went on. "But a phoney by-election is not the forum for these debates."

Her comments came moments after Mr Davis submitted his application to Chancellor Alistair Darling for the stewardship of the Three Chiltern Hundreds - the necessary formality for resigning a Commons seat.

Speaking afterwards on the steps of the Treasury, Mr Davis said the public would view the Prime Minister as "gutless" if Labour did not take part in the by-election.

Mr Davis's announcement last week that he would resign his seat and fight a by-election after the Government's narrow victory over 42 days has been met with Tory anger. But Mr Davis insisted the majority of his constituents understood he was making a principled stand in defence of civil liberties.