Lord Frost, a Brexit minister, has resigned from the Cabinet 'because to Plan B Covid measures.'

Boris Johnson’s government was thrown into panic last night as Brexit minister Lord Frost dramatically quit the cabinet.

Lord Frost is said to have tendered his resignation a week ago, but was persuaded to stay until January.

The peer - who negotiated Britain’s departure from the EU, and was tasked with ironing out the final details of the future relationship - reportedly resigned over the “political direction” of Boris Johnson ’s government.

In his letter, Lord Frost, who attended cabinet, said his resignation would take "immediate effect" and spoke of his desire to see a "low-tax" economy.

He wrote: "I hope we will move as fast as possible to where we need to get to: a lightly regulated, low-tax, entrepreneurial economy, at the cutting edge of modern science and economic change.

He added that measures to reopen the economy in July "did not prove to be irreversible" - adding: "I hope we can get back on track soon and not be tempted by the kind of coercive measures we have seen elsewhere."

And he expressed his wish that the UK would become a "lightly regulated, low-tax" country.

In his reply, Mr Johnson he was "very sorry" to have received his resignation.

Lord Frost's departure was described as a "watershed moment" by prominent Brexiteer Tory Andrew Bridgen.

He told Times Radio it was a "devastating blow for the Government and the Prime Minister" and suggested that many Conservative colleagues would be considering the PM's future over Christmas.

A senior Government source told the Mail on Sunday Lord Frost's exit had been prompted by the introduction of ‘Plan B’ Covid measures.

It’s the latest in a series of damaging blows to the Prime Minister, following a series of stinging rebellions from Tory backbenchers in Covid votes, and an embarrassing defeat in the North Shropshire by-election.

The news comes just a day after The UK admitted there will be no deal this year over the consequences of the PM’s Brexit pact in Northern Ireland.

Lord Frost announced a solution “needs to be found urgently early next year” to the Northern Ireland Protocol after missing his own deadline.

Previously the Brexit Minister had claimed it was “an issue for this autumn, to be settled one way or the other”.

It means some checks that were repeatedly delayed will now come in on January 1 in the absence of a deal.

Ministers had to issue a statement exempting goods that move from the island of Ireland to Great Britain from these checks.

But they will apply to “all other inbound goods” and include the “pre-notification of agri-food imports”.

The UK has admitted there will be no deal this year over the consequences of Boris Johnson ’s Brexit pact in Northern Ireland.

Brexit Minister Lord Frost announced a solution “needs to be found urgently early next year” after missing his own deadline.

Previously he’d claimed it was “an issue for this autumn, to be settled one way or the other”.

It means some checks that were repeatedly delayed will now come in on January 1 in the absence of a deal.

But the UK has still not carried out its threat to trigger ‘Article 16’, a move that would effectively unilaterally suspend the treaty and prompt fresh chaos.

The minister said today: “For as long as there is no agreed solution, we remain ready to use the Article 16 safeguard mechanism if that is the only way to protect the prosperity and stability of Northern Ireland and its people.”

Lord Frost has been mired in talks on the Northern Ireland Protocol, which Boris Johnson signed as part of his Brexit deal with the EU in 2019.