Lord Frost has told Boris Johnson that he is resigning from the Cabinet due to “disillusionment” with the direction of the Government.

The Brexit Minister, who was leading Mr Johnson’s post-Brexit negotiations with the EU, is said to have quit over the Prime Minister’s Plan B Covid restrictions a week ago but was persuaded to remain in his post until January.

Lord Frost felt growing “disillusionment” with the “direction” of the Government’s policy, according to the Mail on Sunday.

The resignation of such a close ally creates a major new crisis for the Prime Minister. In a series of Cabinet interventions, Lord Frost resisted Mr Johnson’s National Insurance hike and opposed draconian Covid-19 measures – a new suite of which are now being considered by the Government. 

His interventions have echoed the views of many Tory backbenchers and his resignation is likely to fuel fears about the direction of the Government.

It comes after Mr Johnson faced a rebellion by MPs over the introduction of the tougher Covid restrictions.

A senior minister said they were not at all surprised by Lord Frost quitting the Government, adding: “I know he opposed Plan B. The Prime Minister’s supporters are the ones who are least keen on the restrictions. The ones who want to undermine him want the restrictions. Frost going just proves that.”