A 48-year-old Labour-supporting businessman from Gloucestershire surprised himself yesterday by arriving in Sedgefield to begin his campaign to oust Tony Blair from Parliament.

"I am middle-class from middle England, but I feel bloody angry about the war," said Jonathan Cockburn who has formed his own party, the New Socialist Party, to contest the Sedgefield seat in the General Election, which is expected next May.

"I'm a businessman not a politician, but I feel as if I've been kicked in the stomach by Tony Blair," he said.

"I've benefited from a middle-class background - grammar school, university, employed all my life, but those people in Fallujah in Iraq who've had their families bombed haven't had those opportunities."

In December 2002, Mr Cockburn, who has voted Labour all of his life, wrote to Mr Blair in Downing Street complaining about his "arrogant and foolish" foreign policy. He ended the letter with what appeared to be an idle threat, saying that if Mr Blair went to war with George Bush, he would stand against him.

Matters crystallised in March 2003. "I heard Mr Blair on the car radio and for the first time in my life I found myself shouting at the radio," said Mr Cockburn, who is director of a firm that manages car parks. "It was like a religious conversion. I went home and said to my wife 'we have got do something about this'."

Yesterday, the father-of-three began his campaign, touring Newton Aycliffe and Sedgefield handing out his first batch of 5,000 leaflets.

Mr Cockburn, who was accompanied by a TV cameraman making a documentary about the campaign, has written a manifesto pledging to stop university top-up fees and foundation hospitals.

He would happily withdraw from the election and vote Labour should Gordon Brown replace Mr Blair as party leader, and he knows he has a mountain to climb if he is to overturn Mr Blair's 17,713 majority.

"I would call it a success if I were to keep my deposit," he said.