It’s “lunacy”, “facile and divisive self-indulgence”, “ludicrous” and a “circular firing squad”. Just some of the attacks on Sir Simon Clarke after his “Rishi must go” outburst.

His incendiary attack is either a one-man kamikaze mission or the start of a new mutiny by right-wing Tory MPs. So far, however, it’s looking more kamikaze than mutiny.

True, the Middlesbrough South and East Cleveland MP – one of Liz Truss’s leading lieutenants – was one of the 11 rebels in the third reading of the Rwanda bill last week.

But he doesn’t have a reputation as being one of the craziest of the right-wingers and his blistering onslaught against the prime minister in The Daily Telegraph has stunned MPs of all parties.

Politics latest: Reaction to Clarke’s call for PM to go

It’s also true that he was one of the Conservative MPs who submitted a vote of no confidence in Theresa May’s leadership in 2018. So he’s got form as a political assassin.

But even some of Mr Sunak’s harshest critics will regard some of his language in his Telegraph article as grossly over the top and view his act of treachery as total madness.

Where his arguments appear deeply flawed are where he quotes at length the Telegraph’s YouGov MRP poll last week predicting a Tory wipeout on the scale of the Tony Blair landslide in 1997.

That poll, however, has been strongly criticised – not least by the pollsters YouGov, who claimed the Telegraph had distorted its findings – and the Tories’ election guru Isaac Levido told Conservative MPs last week to ignore it.

And some of Sir Simon’s claims, surely, are wide of the mark. Tories out of power for a decade? Really? Extinction if Nigel Farage comes back? Apocalyptic, to say the least.

Rishi Sunak – uninspiring and the main obstacle to recovery, gone from asset to anchor? And then this wounding blast: “He does not get what Britain needs. And he is not listening to what the British people want.”

Those are the sort of criticisms the prime minister gets from the Labour Party. No wonder the furious reaction of senior colleagues is that Sir Simon – knighted in Liz Truss’s resignation honours – is doing Labour’s work for them.

A change of leader and the Tories would recover strongly this year, he claims. That surely has got to be one of his more preposterous claims. He even acknowledges that many MPs will claim the party would look ridiculous.

But “meekly sleepwalking towards an avoidable annihilation” would be more ridiculous, he writes. Changing leader would give the party a fighting chance, he claims.

Well, the only fighting that’s going on is between Conservative MPs. No wonder sensible senior figures like Damian Green, Sir Liam Fox, Dame Priti Patel and Sir David Davis have denounced and disowned him.

Is Sir Simon proposing to stand as a stalking horse in a leadership contest, like Sir Anthony Meyer against Margaret Thatcher in 1989, in what was the beginning of the end for her premiership?

Would he attract much support? Unlikely. So far, there doesn’t appear to be the appetite among Tory MPs for a mutiny. Which – so far – leaves Sir Simon exposed as a one-man kamikaze squad.