Boris Johnson’s Tories have established their biggest lead over Labour for two years, a monthly poll of polls has revealed, as the Prime Minister issued fresh warnings about a financial crash under Labour.

Mr Johnson warned today that Jeremy Corbyn would lead the country into a financial crisis as soon as he took office, with large public borrowing plans undoing the reduction in sovereign debt by Tory austerity.

"What Labour would do, I'm afraid inevitably, is take a sledgehammer to the economic success of this country," Mr Johnson said at the Welsh Tory Manifesto launch on Monday afternoon.

"I said that every Labour Government ends in economic crisis. The difference with this Labour opposition is they propose to begin with economic crisis," he said.

The new poll shows the Tories with the same 13 per cent lead that Theresa May had at the same point in the 2017 campaign with two and a half weeks to go - before her bungled manifesto launch led to a collapse in her support to just two per cent by election day.

It predicts an 80-seat majority for the Tories.

The monthly poll of polls shows November was the best month the Tories have had since the last election with the Tories on 43 per cent against Labour’s 29.9 per cent.

It would put the Tories on 365 seats and Labour on 202, while the Lib Dems on 15.1 per cent would get 20 seats, according to the analysis by Electoral Calculus.