MP Ann Widdecombe has defended her decision to defy her party and support the Government in a crunch vote over plans to detain terrror suspects for 42 days.

Speaking after the vote, the former home minister said she had stuck to her position because fighting terrorism was more important than fighting Gordon Brown.

The Prime Minister narrowly avoided a defeat on the measure and Ms Widdecombe was the only Conservative MP to back the plan.

Asked if she thought her party’s opposition to the detention laws had been motivated more by a desire to embarrass Labour rather than because it genuinely opposed the plan, she said:

“One has to keep a sense of proportion of these things. If we had been voting on something that would bring down the Government, that would have been something on an entirely different scale.

"But all that would have happened if the Government had lost would have been a vote of confidence that Gordon Brown would have won.”

She said she had come under no pressure from party whips to change her mind. “Everyone knew what my views were. I have always been prepared to go up to 90 days but I would not want to go up much beyond that - I would have to look at the merits of the case.”

Meanwhile, Sittingbourne and Sheppey Labour MP Derek Wyatt said the extended period of detention was needed because the country was under the constant threat of terrorism.

He said: “You cannot have the kind of much more liberal regime [that opponents argued for] because we are threatened every day and it is our job as a Government to protect people. I voted for it because, as a computer expert, I know from my discussions with the Met Police and the intelligence services that terrorists encrypt their hard discs for much longer than 28 days and we do not have always have the expertise needed to unencrypt a hard disc. Often we might find records and e-mail tracking which we can only get to via a server, which may be in Afghanistan and Iraq. That means we have to work within their laws and it might take months [to get permission] and also exposes what you are doing when you want to be doing it covertly.”

Fellow Medway Labour MP Bob Marshall Andrews was among the 37 rebels who voted againt the Government.