Disgraced former MP Eric Joyce has insisted he’s not to blame for, well, everything that’s happened in British politics since he started a brawl in a House of Commons bar.

The butterfly effect theory runs that if Joyce had not kicked off in Stranger’s Bar one night in 2012, then the nation would look very different indeed.

The fracas, in which Joyce headbutted Tory Stuart Andrew and lamped his own party whip Phil Wilson, led to him giving up his Falkirk seat and quitting the Labour party.

That led to the infamous Falkirk selection fight which saw accusations that the contest was rigged by the unions and the Labour left.

As a result Ed Miliband drew up new rules for Labour membership, which included the option of paying just a few pounds to join and vote in leadership elections.

That allowed thousands to get involved in the 2015 leadership election and make Jeremy Corbyn leader. Corbyn’s ineffective campaigning and failure to deliver the Labour vote at the Brexit referendum is blamed by some for the Leave victory. And as a result of that Nicola Sturgeon is champing at the bit for another independence referendum and this week Theresa May called an early general election to essentially set up a five-year Brexit parliament.

“It’s quite a nice theory,” admits Joyce. “And on one level it’s factually true. But much as I like to self-aggrandise myself, if it hadn’t been Falkirk it would have been somewhere else.

“People were saying to me that the left were making a big push in Paisley to get rid of Douglas Alexander, then my thing came along and they made their stand in Falkirk rather than Paisley.

“Until that point I’d had running battles with the left, but I battered them down every year.”

After Joyce left Labour, Karie Murphy, now a key figure in Corbyn’s office and inner circle and close to Unite boss Len McCluskey, tried to win the nomination to replace him. But questions were raised about the role of Unite in the process and it was claimed that locals had been signed up to the party without their consent. As the scandal grew, then-Labour leader Miliband announced his fateful reforms to party membership in an effort to draw a line under it. (Labour later cleared Unite of any wrongdoing).

Joyce told me: “Ed was very weak with the left and he had this terrible gullibility. If it hadn’t had been Falkirk the same issues would have surfaced somewhere else.”

He has largely kept his head down since stepping down from Parliament two years ago, other than the occasional blog on the state of the Labour party or the issue of Scottish independence – which he now supports. He’s canned plans for an autobiography but claims he’s adapted some episodes from his life for a thriller instead.

However, in this rare intervention he’s scathing about Corbyn and also about the moderate Labour MPs who oppose him.

He said: “Jeremy Corbyn’s politics are quite literally bonkers.

“When I was an MP I took a lot of interest in Africa. I used to do quite a lot of stuff with Jeremy, he was really engaged and he just stayed behind the scenes focusing on his constituency and his issues. Then occasionally he’d make these bonkers speeches and I’d stay away.”

But he claims the current crop of MPs don’t have the skills to deal with the Corbynista tide.

The former soldier explained: “When I got selected I treated it like a campaign, I located in the constituency, contacted everyone, eventually I got selected, and when the left put their head above the parapet I knocked them down.

“A lot of current MPs got where they are by patronage, they’ve not had to fight battles, they’ve been special advisers. And when it came to Corbyn they weren’t able to carry their local party.

“Politics is all about numbers and organising. And while the Blairite bits of Labour write articles for Progress and tweet, the left just go and get the numbers.”

No longer a member, but describing himself as a Labour supporter, Joyce, an MP for 15 years from 2000, is gloomy about his former party’s prospects.

“It’s hard to see Labour in power before 2025, if ever," he said. "There was no coup, Labour had a nervous breakdown.”