BORIS Johnson's ethics adviser quit after the UK Government put him in an "impossible and odious" position, his resignation letter to the Prime Minister has revealed.

Lord Christopher Geidt stepped down as Johnson's ethics tsar quit just days after he said it is “reasonable” to suggest the Prime Minister broke the ministerial code over coronavirus lockdown-busting parties in No 10.

He was the second person to resign from the post in two years, pouring further pressure on a Prime Minister who has already lost the confidence of more than 40% of his own MPs.

In his resignation letter, Geidt said Johnson had considered action which risked a deliberate breach of his own ministerial code.

Geidt wrote that he had been "tasked to offer a view about the Government's intention to consider measures which risk a deliberate and purposeful breach of the Ministerial Code".

In his reply, the Prime Minister said that this request related to "potential future decisions related to the Trade Remedies Authority".

The TRA is the body set up to protect UK industries from unfair practices or unexpected surges in imports.

These remedies usually take the form of additional duties on those imports, effectively making UK-produced products more competitive.

The body was set up following Brexit, as such measures were handled by the European Union’s institutions while the UK was in the single market.

READ MORE: Boris Johnson 'considering scrapping ethics adviser role', Downing Street says

Geidt said that the Government's request had put him in "an impossible and odious position" and he was left with no choice but to resign.

The peer wrote: "The idea that a Prime Minister might to any degree be in the business of deliberately breaching his own Code is an affront. A deliberate breach, or even an intention to do so, would be to suspend the provisions of the Code to suit a political end.

"This would make a mockery not only of respect for the Code but licence the suspension of its provisions in governing the conduct of Her Majesty's Ministers. I can have no part in this ... I therefore resign from this appointment with immediate effect."

Geidt also said that he had believed "it was possible to continue credibly as independent adviser, albeit by a very small margin" in the wake of "inconsistencies and deficiencies" on Johnson's part in relation to the partygate scandal, which saw the Prime Minister fined for breaking the Covid laws he had put in place.

READ MORE: Ministerial standards adviser quits as PM contradicts his Patel bullying advice

He said that Johnson had failed to address concerns about having breached “the Nolan Principles (on leadership, in particular)” and expressed “frustration” that the Prime Minister had avoided making public statements on his own behaviour and the ministerial code.

Geidt added: "Moreover, I regret the reference to 'miscommunication' between our offices, with the implication that I was somehow responsible for you not being fully aware of my concerns."

Johnson's reply was published alongside Geidt's letter.

In it, the Prime Minister says the resignation "came as a surprise" as the peer had agreed to stay on until the end of the year.

The National: Prime Minister Boris Johnson speaks during a press conference in Downing Street, London, following the publication of Sue Gray's report into Downing Street parties in Whitehall during the coronavirus lockdown. Picture date: Wednesday May 25, 2022..

The Tory leader wrote: "You say that you were put in an impossible position regarding my seeking your advice on potential future decisions related to the Trade Remedies Authority.

"My intention was to seek your advice on the national interest in protecting a crucial 
industry, which is protected in other European countries and would suffer 
material harm if we do not continue to apply such tariffs.

"This has in the past had cross-party support. It would be in line with our domestic law but might be seen to conflict with our obligations under the WTO. In seeking your advice before any decision was taken, I was looking to ensure that we acted properly with due 
regard to the Ministerial code.

"You have carried out your duties admirably under very difficult circumstances. We have discussed the burdens placed on you by this increasingly public role, and the pressures that would be felt by anyone in your position. On behalf of the Government, I would like to renew my thanks for all your work."

The Prime Minister's suggestion that the "increasingly public role" played by Geidt had contributed to his decision to leave was echoed by Dominic Raab on Thursday morning.

The Justice Secretary suggested that a "pretty rough grilling" given to Geidt by MPs on the standards committee could have contributed to his decision.