"It's them that's given me a political home, so why would I knife them in the back?" he said in January, when asked about the Conservatives.

On Monday, it was a full frontal assault as Mr Anderson, having been suspended from the party last month after claiming "Islamists" had "got control" of London mayor Sadiq Khan, joined Nigel Farage's Reform UK, in a wounding blow to Rishi Sunak.

Mr Anderson, in a terse media briefing, told his audience that he had "done a lot of soul searching" and had decided to quit the Tories to "get my country back", as he launched a broadside against old colleagues for stifling "free speech" and trying to shut him down for "speaking his mind".

"People will say that I've took a gamble. And I'm prepared to gamble on myself," he told his audience. "And like millions of people up and down the country, all I want is my country back."

His defection is an undoubted coup for Reform, the successor to Mr Farage's Brexit party, which plays into the rightwing populism of Donald Trump and carries the slogan: "Make Britain Great Again."

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For Mr Sunak, there is no other way to spin this than a body blow. Within hours of Mr Anderson's defection - and the warning from Reform UK's Richard Tice more are to come - other Conservative MPs were coming forward to express regret, not anger, over the defection, as they sided with Mr Anderson's sentiments, throwing the spotlight once more on the deep party divisions that the current prime minister simply cannot contain.

The New Conservatives grouping on the right of the party issued a statement saying "we cannot pretend any longer the plan is working" as they urged the prime minister "to change course urgently".

Many Conservative MPs on Monday wanted to keep their heads down. Some are sympathetic to Mr Anderson, others are furious with him, with one former cabinet minister telling me he was a man "who put his ego and personal status above all public interest" and said Mr Anderson only wanted to "seek attention and headlines rather than serve the public. It's exactly the unprincipled behaviour the public loathe". Another minister texted that Mr Anderson was "just an angry rude man".

Speak to those in cabinet and government, and the message you get back is "disappointment" and "sadness" it's ended up this way, but it's election year and they have to get on with it. Those around the prime minister don't want to go to war with Mr Anderson - perhaps in order not to further fire up this tribe. "It's not ideal," said one senior figure, "he's ended up in a party he doesn't really want to back."

Another Number 10 figure said that while they are disappointed it came to this, no one individual was bigger than the team. "Sometimes you have a great player but if they disrupt the whole team, you don't want them on the team. We're getting on with it, it's election year," they said.

Government figures also batted off talk among MPs about a divided Number 10 as some Conservative sources talked about the mood of gloom enveloping the prime minister's team, with one source telling me Mr Sunak's inner circle were united in the decision to suspend Mr Anderson - although they were prepared to have him back if he apologised.

But, how ever they try to downplay this, Mr Anderson is the symptom of a much deeper problem for the Conservative Party as it heads into an election, not only miles behind Labour but now having to face off Reform to the right, with the party now polling around 12%.

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The Lee Anderson megaphone will undoubtedly only get louder in the coming weeks.

A taster of what's to come came from Mr Tice after the media conference when he told me that the Tories deserved to be "punished" for breaking Conservative manifesto promises on immigration.

"We are here to replace the Tories in many areas and we are here for the medium term," Mr Tice told me. "The Tories are doomed. They are toxic, they are being punished at the polls and quite rightly."

What we have been reminded of today is Mr Sunak's inability to hold together the coalition that Boris Johnson managed to stitch up on the back of Brexit in 2019.

There are those on the right of the Conservative Party that will now argue, even more loudly, that Mr Sunak must tack to the right on immigration, environment and gender issues, in order to win back voters in seats like Mr Anderson's Ashfield, while along the blue wall of voters in the South, South West and Home Counties, Mr Anderson's version of Conservatism is an anathema to them. And all the while, instead of talking about the economy and Conservative policies, the party is locked in the death spiral of internal war.