Keir Starmer ’s Labour Party prepared an emergency blueprint for Government during the months of chaos in the Tory party.
The Mirror understands a manifesto was drawn up over the summer as the Conservatives descended into open warfare and ousted two Prime Ministers.
The document formed part of Labour's contingency measures should the Government have collapsed at any point - forcing a snap general election.
A senior Labour source told The Mirror: “We always wanted to make sure we were ready for an election.
“Given the chaos in the Tory party there were moments in 2022 when it looked like they could collapse at any time.
“We knew we had to be ready and part of that was having a manifesto in the drawer ready to go if there was an election that was called.”
Only a handful of officials have seen the provisional blueprint for Government that was written by the Labour leader's outgoing policy adviser Claire Ainsley.
One shadow minister also said they had been put on "accelerated policy" development to be "held in reserve" in case of a general election.
In the New Year Labour is expected to continue work on a manifesto that will eventually be presented to the public at a general election which is now likely to be held in 2024.
The party will have to outline its vision for the country including policies on tax and spending, the climate crisis, public sector reform, and tackling the cost-of-living crisis.
In November Mr Starmer described his predecessor Jeremy Corbyn's manifesto for the 2019 general election as "history" and would go to the country with a "slim" and "focused" programme for No10.
It comes after an extraordinary year of Tory turmoil, with MPs first ousting Boris Johnson from Downing Street in July over multiple scandals, including Partygate.
Just months later Liz Truss was forced from office after her disastrous mini-Budget sparked panic in the financial markets and sent the Tories' poll rating plummeting.
Labour has since enjoyed a commanding lead in the polls and last month one forecast predicted a 314-seat majority and the Conservatives' worst result in a century.
But on Monday the ex-Tory Prime Minister Theresa May, who blew her majority in Parliament with a snap general election in 2017, insisted the Tories could still win the next vote.
She told BBC Radio 4's PM programme: "There's no doubt that the mini-Budget had an impact on the Conservative Party's reputation for sound money and sound public finances.
"But I think what we've seen already with the new Chancellor and a new Prime Minister is taking the process of re-establishing that reputation".
The former premier claimed: "I think from everything we've seen from Rishi so far, that actually he's going to be able to turn that round by the next election.
"I see that we can in those two years show people that a Conservative government can be on their side and that he can turn it round and we can win that election."
