A Very British Coup 35 years on

In 1982, Chris Mullin published a political thriller about what might happen if a radical Socialist took the leadership of the Labour party and became Britain's prime minister. Channel 4 made a hit TV version. Chris Mullin has been at work on a sequel - but is the election of Jeremy Corbyn as Labour leader likely to supply some new plotlines?

It is 35 years since Chris Mullin, not yet a Labour MP, decided he'd better knuckle down to a political thriller he planned to write. With Margaret Thatcher in Downing Street, Jim Callaghan was about to stand down as Labour party leader. There was speculation about what would happen were his successor a left-winger.

"I was on a train with colleagues coming back from the autumn party conference and we discussed how the establishment would react if Tony Benn became Labour leader.

"My friend Stuart Holland, who was already an MP, said that by a Greek swimming pool that summer he'd tapped out the opening chapters of just such a novel. Then Peter Hain piped up and said he and a colleague had also just submitted a similar idea to publishers. So I thought I'd better get on and write it."

A Very British Coup emerged in 1982. It's the story of the brief premiership of Harry Perkins, a former Sheffield steelworker who unexpectedly reaches Downing Street. His radical policies include ridding the UK of American nuclear weapons. But Perkins falls victim to a vicious conspiracy of Whitehall mandarins, MI5, newspaper proprietors and the CIA. The hands of the BBC are also far from clean.

Initially the book was a modest success.

"By and large the right-wing press said it was preposterous and the more liberal papers said it was an amusing fantasy. Sales really took off when Channel 4 made a series of it in 1988. It won several Bafta awards and in America it took the Emmy for Best Drama," Mullin explains.

Perkins was played by Irish actor Ray McAnally. Alan Plater's script made several changes to the storyline but the big change was the ending.

"The TV people thought I had allowed Perkins to cave in and resign too easily when he's blackmailed. The adaptation shows him fighting back more and the ending is a bit more ambiguous."

In 2012, as Secret State, the novel was filmed once again for TV starring Gabriel Byrne, though this time to less acclaim.

Mullin says Harry Perkins was never meant to represent any real-life figure in 1980s politics.

"I didn't become an MP until 1987 but I was already known as a Benn supporter. I went out of my way to ensure Perkins, with his working-class background, wasn't like Tony at all. But I did show him a draft and he didn't like that I described Perkins as a big tea-drinker, which Tony was famous for. So that came out. Tony was a bit suspicious of the book but when the TV series was on he was fascinated and phoned me after every episode to discuss it.

"There were some establishment dirty tricks in my novel which later turned out nearer the truth than I imagined. When the agent Peter Wright published Spycatcher (in 1987) he famously claimed that the Security Service had 'bugged and burgled its way across London' - my conspirators were far less ambitious."

One of the book's concerns is how the media react to a radical left-winger in Downing Street.

"Of course Jeremy Corbyn is only party leader, he's not Prime Minister. But in the past few days you've already had the papers digging up things from his past in exactly the way they do in my novel.

"For now we're a long way from Jeremy forming a government and to see that happening would take a large intellectual leap. But if he ever threatened to do so, I imagine the establishment would start behaving very badly," Mullin speculates.

"I don't suggest that everybody would behave as they might have done 30 or 40 years ago. For example I think the intelligence services have largely been cleaned up. I can remember one Tory Home Secretary whispering to me that they'd 'got rid of a lot of the dead wood'."

One of the most entertaining aspects of Mullin's book was the treatment of the Americans, where he allowed himself a degree of parody.

"In the 1980s, the row about US cruise missiles stationed in Britain helped make my novel feel topical. Today the focus is on the future of Trident which probably Washington is less interested in."

Mullin left parliament in 2010 after 23 years as an MP and three ministerial jobs. His three volumes of political diaries have been well received. Now he's plotting a return to the world of the conspiracy thriller.

"Every so often, people in the film world call up enquiring about a sequel. I've written a few thousand words and the working title is The Friends of Harry Perkins. It starts with Harry's funeral. But Jeremy becoming party leader is making people interested in possible parallels and maybe I'll need to go back to the drawing board.

"But the truth is that none of us know what will happen in the next couple of years. That's what makes it so interesting."