Two of the county's MPs say they will support David Davis on the campaign trail during the by-election triggered by the shadow home secretary's decision to quit as an MP.

Medway's Labour MP Bob Marshall-Andrews and Ashford MP Damian Green, who is the Conservatives' shadow immigration minister and worked as part of Mr Davis's team, both back the shock move, taken over the issue of holding terror suspects for 42 days.

Mr Marshall-Andrews has already said he is prepared to lose the party whip.

An avid campaigner on the subject, he said: "I've written to him inviting myself to speak on civil liberty issues and would be delighted to do so. I feel strongly about civil liberties and if speaking out costs me the whip, then so be it."

Labour has not yet announced whether it will put up a candidate in the by-election, which would affect a decision on whether Mr Marshall-Andrews has broken party rules by offering support to Mr Davis.

Mr Green said: "I will be going up to campaign for him. It is an issue he feels very strongly about and he is perfectly right to identify that. The Government is trampling on our civil liberties; he feels the way he does and this is the way he has chosen to do it."

Meanwhile, former home office minister Ann Widdecombe, the only Conservative MP who voted for the Government over the extended detention period, said Mr Davis needed to separate the issue of the 42 days from his other concerns about civil liberties.

"It is a bold step by a bold man," she said. "One of the problems he has got is that he has swept a lot of other issues, like ID cards, CCTV cameras and hate crime in as well.

"My concern is that he will be forced by events into having a referendum on 42 days. Most people do share his views on the broader picture but most people do not share his views about 42 days."

There was also a cautious reaction from Faversham and Mid Kent MP Hugh Robertson (Con). He said: "It is always good to see MPs acting on a point of principle but I am not sure what he is hoping to achieve."