LORD Frost, who was the UK’s chief Brexit negotiator during the trade talks with Brussels, has been made a full member of Boris Johnson’s Cabinet, Downing St has announced.

The 55-year-old former diplomat had been tipped to become the Prime Minister’s National Security Adviser but instead will now become a Minister of State at the Cabinet Office, working alongside Michael Gove, with a view to “maximising the opportunities” of Britain’s departure from the EU.

Lord Frost will replace Mr Gove as the Chairman of the UK-EU joint committee on the Withdrawal Agreement, a key role as Northern Ireland faces post-Brexit trade disruption.

“I am hugely honoured to have been appointed minister to take forward our relationship with the EU after Brexit,” declared the peer.

He added that he would be standing “on the shoulders of giants”, particularly of Mr Gove, “who did an extraordinary job for this country in talks” with Brussels.

Mr Gove said Lord Frost’s move was a “great appointment”, adding that there was “no-one better to take forward our post-Brexit relationship with the EU”.

Last week, the peer blamed the severely strained tensions with the EU on Brussels struggling to accept a “genuinely independent actor in their neighbourhood”.

He told MPs that the EU needed to adopt a “different spirit” to ease the “more than bumpy” relationship since the end of the post-Brexit transition period on December 31.

A statement from No 10 said: “The Queen has been pleased to approve the appointment of Lord Frost CMG as a minister of state in the Cabinet Office.

“Lord Frost will be a full member of Cabinet. His appointment will take effect from March 1 2021.”

When previously reversing the decision to appoint Lord Frost as security adviser, the PM’s spokesman said he had been appointed representative for Brexit and International Policy and head of a new International Policy Unit in No 10.

“He will lead the UK’s institutional and strategic relationship with the EU and he will help drive through changes to maximise the opportunities that flow from the deal we reached with the EU,” explained the spokesman.

Lord Frost, a former career diplomat who went on to become the Chief Executive of the Scotch Whisky Association, served as a special adviser to Mr Johnson when he was Foreign Secretary.

After succeeding Theresa May in No 10, the PM appointed the Brexit true believer to lead negotiations with Brussels, opposite the EU’s Michael Barnier.

Lord Frost is an ally of Mr Johnson’s controversial former chief adviser, Dominic Cummings, but did not follow him out of No 10 following his dramatic departure amid a bitter power struggle.