British Prime Minister Rishi Sunak’s attempts to lead the Tories to victory at the next general election in two years’ time are being seriously undermined by his own cabinet colleagues, including notably the chairman of the Conservative Party whom he had to sack on Sunday morning for not being entirely honest about his tax affairs.

The ignominious end of Nadhim Zahawi’s political career is almost a Shakespearean tragedy for the man who was born in Iraq into a Kurdish family, came to Britain as a refugee when he was a boy, went into business and co-founded the polling company YouGov, became a Tory MP for the Bard’s Stratford-on-Avon, entered the cabinet, was a very successful “vaccines minister” under Boris Johnson and was briefly chancellor under Liz Truss.

Unfortunately and also ironically, when he was chancellor and in charge of Her Majesty’s Revenue and Customs, he was also being investigated by the tax authorities who fined him a reported £4.8 million in back tax and a penalty.

He did not breathe a word about this to either Truss or to Sunak, who appointed him Conservative Party chairman in charge of readying the troops for the election battle that lay ahead.

To compound his grave error of judgement, Zahawi, 55, threatened legal action to try to shut down journalists who began asking questions about his tax affairs. But as the story unravelled, Zahawi claimed he had been “careless” rather than set out deliberately to dodge tax through off-shore arrangements.

Fatally for him, the government’s ethics adviser, Laurie Magnus, asked by the Prime Minister to report back as quickly as possible on the facts of the case, told Sunak: “I consider that Mr Zahawi, in holding the high privilege of being a Minister of the Crown, has shown insufficient regard for the General Principles of the Ministerial Code and the requirements in particular, under the seven Principles of Public Life, to be honest, open and an exemplary leader through his own behaviour.”

He commended Zahawi “for his willingness to assist with my inquiry” before delivering his coup de grâce: “These factors, however, cannot mitigate my overall judgement that Mr Zahawi’s conduct as a minister has fallen below the high standards that, as Prime Minister, you rightly expect from those who serve in your government.”

In his dismissal letter, Sunak told Zahawi: “When I became Prime Minister last year, I pledged that the government I lead would have integrity, professionalism and accountability at every level.

“That is why, following new information which came to light in recent days regarding your personal financial arrangements and declarations, I asked Sir Laurie Magnus, the independent adviser on ministers’ interests, to fully investigate this matter. You agreed and undertook to cooperate fully with the inquiry.

“Following the completion of the independent adviser’s investigation — the findings of which he has shared with us both — it is clear that there has been a serious breach of the Ministerial Code. As a result, I have informed you of my decision to remove you from your position in His Majesty’s Government.”

In his response, Zahawi did not address the question of his tax penalty but instead blamed the media: “I am concerned, however, about the conduct of some of the fourth estate in recent weeks. In a week when a Member of Parliament was physically assaulted, I fail to see how one headline on this issue ‘‘The Noose Tightens’ reflects legitimate scrutiny of public officials. I am sorry to my family for the toll this has taken on them.”