Interviewed while Mr Major and his wife Norma chatted to his workers, Sir Anthony cast doubts on Mr Blair's fitness for office.
Comparing the two leaders, he said Mr Major had been Foreign Secretary and Chancellor before becoming Prime Minister. "The other one, I don't think he has done a job in his life and that is the top and bottom of it."
Tory party officials said he was furious at the way Labour had played up a visit by Mr Blair last September after the TUC conference, when he described the Labour leader as "a refereshing politician".
Mr Blair described the trade union relations in the JCB plant in his keynote speech to the party conference. "We are on the same side, the same team, Britain united, and we will win," he said.
Sir Anthony yesterday said he was backing the Tories to win the election. 'I am not a Labour voter. I haven't been nor will I be. We invite politicians of all colours here. Blair came as a very welcome visit. He was impressive but he has never been tried as Prime Minister."
Sir Anthony's repudiation of Mr Blair came as a further boost to Tory morale, seeking what the Americans call 'big Mo' - the momentum to carry their campaign forward after being stalled for three weeks on sleaze. But it carries clear risks for Mr Major. Sir Anthony is a strong Euro- sceptic who is opposed to the single currency.
"Having one currency in Europe, everybody knows just doesn't end there - you have a central bank, a common interest rate; it's a political thing, we end up with a federal Europe which I'm really against."
Sir Anthony is rated one of the richest men in Britain, with a fortune based on the machine that bears the family initials and has become synonymous with industrial diggers. He said he had won a lot of money betting on Mr Major to win last time, and had bet on him again to win.
He refused to confirm he was a donor to party funds, but Mr Blair told the party conference last year that Sir Anthony was one of the main backers of the Tory party, and it is believed he is among the top earners who have helped to fill the Tory war chest for the election.
A Labour spokesman last night denied Mr Blair had said Sir Anthony Bamford was one of the party's backers. A spokesman said: 'We have never said that hundreds and hundreds of business people are all going to start voting Labour. What we have said is that there's a new relationship with Labour. They are prepared to talk to Labour in a way which has not happened in the past. We welcome that new and changed relationship."Reuse content