The fruit and veg man, who stood both in the 2007 Northampton local election and 2005 General Election, declared he would take part in the fight sparked by Shadow Home Secretary Mr Davis's shock resignation from Parliament over the 42-day detention issue.

Mr Fitzpatrick, known as Fitzy, said: "I think what he's done is crazy. I'm an independent-minded man, but I think what he's doing is barmy. I can't understand it.

"So I'm going to pack up my business for a month and have a go at it.

"I've got a few bob behind me, so I can back myself and all the people I've spoken to on the stall have said, 'Go for it'.

"I think people will back what I say. I'm not a politician, I'm a fruit and veg man, but I'll certainly have a go and I'll do whatever it takes.

"Once I get going, there'll be no stopping me."

The Yorkshire by-election was sparked after Mr Davis resigned because of his opposition to Government plans to allow the police to detain terrorism suspects for up to 42 days without trial.

Mr Davis will fight in the election and has claimed the vote will act as a mini-referendum on anti-terror legislation.

But Fitzy will go head-to-head with him on the terror debate.

He said: "I agree with the whole 42 day thing and I think the public do too.

"After all, the police have asked for it, so I think we should give it them.. They're not doing it for the sake of it."

Mr Fitzpatrick fought for the Northampton South seat in the 2005 General Election, but finished next to last, securing only 346 votes.

Two years later, he stood for the Northampton Castle ward in the 2007 local election, again finishing next to last and this time securing 210 votes.

He could stand a chance of improving his support in the battle against David Davis as, so far, the Liberal Democrats have said they will not stand and Gordon Brown has not indicated whether his party will contest the seat.