Labour were backed to win the next general election after a YouGov poll gave them a 17 point lead over the Conservatives on Monday.
It's the biggest lead Labour have enjoyed since 2001 when Tony Blair was prime minister and showed them taking 45% of the vote.
Labour shortened to 1.625/8 from 1.75/7 on the Exchange to win the next election while the Conservatives drifted to 2.568/5.
Labour touched 1.584/7 - their lowest odds ever to win the next election - on Monday and again today.
The price on a Labour majority 3.02/1 is coming in - and it is shorter than a Conservative majority 4.67/2 - but the favourite outcome remains a hung parliament at 2.1211/10.
Ahead of his highly-anticipated speech to the Labour party conference Keir Starmer is 1.8810/11 favourite to be Britain's next prime minister.
Kwarteng chaos=Lab government in waiting?
The poll was conducted after last Friday's seismic mini-budget in which chancellor Kwasi Kwarteng unleashed historic tax cuts, ditched the cap on bankers' bonuses and announced huge increases in borrowing which sent markets into a tailspin.
That undermined confidence in the UK government and economy.
Yesterday, the pound plunged to an historic low as investors baulked at the Kwarteng's budget.
Last night, it was rumoured that the chancellor may have to row back on his budget or he could be forced out. YouGov polling showed only 19% of voters thought Kwarteng's budget was "fair" -- the worst polling figure since YouGov began to ask the question in 2010.
The last few days have been toxic for a party that has already suffered a spectacular decline in fortunes over the last year.
In September 2021, the Tories were 1.454/9 to win the next election, while Labour touched their biggest price of 3.953/1. Earlier last year, a successive Tory majority had shortened to an all-time low 1.738/11.
It's been a punishing 12 months for the Conservatives.
The Betfair Exchange market is up on whether Liz Truss, who became prime minister just three weeks ago, will face a no confidence vote this year.
The odds on her leaving as Conservative leader this year have shortened to 13.5, although they drifted to 14.5 today.
Truss is 2.8 to go next year and 2.66 to leave in 2024 - the year when the next general election is scheduled to take place.
Meanwhile, the mood at the Labour conference is buoyant because, for the first time in many years the party looks like a government in waiting.
For more expert political betting analysis read Paul Krishnamurty's live blog