British PM Boris Johnson's minister David Frost, who led the Brexit negotiations, has resigned from the government, The Daily Mail reported on Sunday.
According to the report, citing Downing Street sources, Frost ought to have resigned in January due to "disillusionment" with the direction of government policy in yet another setback for Johnson.
Later, in the early hours of Sunday, the UK government released Frost's resignation letter in which he stated that he will leave with immediate effect since "Brexit is now secure," and the move broke the news on Saturday night.
The minister also claimed, however, that he had expressed his "concerns about the current direction of travel" to Johnson.
"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.
The outgoing minister said it was a "huge honour and privilege" to work alongside Johnson, whom he called simply "Boris." Frost praised his now-former boss for being "an outstanding leader at a moment of grave constitutional crisis for this country."
Frost added that the UK needs "to learn to live with COVID-19," and expressed a belief that the kingdom "can get back on track soon and not be tempted by the kind of coercive measures we have seen elsewhere."
"Together we have put this country onto a new path. I am confident that under your leadership this newly free Britain can succeed and prosper hugely. I wish you and the Government every success in that," he concluded the letter.
Johnson has already responded to the letter from his minister, starting and ending a typed letter with his signature, and expressing regret over the resignation and thanking him for his work. In the letter, the prime minister called Frost his "EU Sherpa" who was responsible for the smooth withdrawal from the EU in January 2020.
Johnson commended Frost's "hard work, resolve and vision" in achieving the goals of his chief negotiator's work during his term in the government.
"You should be immensely proud of your historic service to this Government and this country," he added.
Frost, a former diplomat, was lauded by Johnson and was a staunch Brexit advocate who helped the prime minister negotiate a revised EU divorce arrangement and a trade agreement.
He was leading an attempt by London to renegotiate aspects of the divorce deal touching the Northern Ireland border before his resignation.
The Northern Ireland Protocol keeps the border with the Republic open while requiring checks on items from the United Kingdom, which has resulted in certain products, such as sausages and oak trees, being prohibited from entering the region under EU regulations.
But according to Daily Mail sources, the minister was not particularly happy about other aspects of the government's foreign and domestic policies.
Frost has reportedly been one of the most outspoken Cabinet members in favor of keeping the country open and avoiding additional pandemic-related legislative controls. He also believed that vaccine passports are an ineffective strategy to curb the spread of the virus.
Now, just as Johnson finds himself in the center of a slew of scandals, particularly since a video emerged showing his workers laughing and joking about a Downing Street party during the 2020 Christmas lockdown, when such activities were banned, he is forced to make cabinet changes sooner rather than later.