In the aftermath of the Donald Trump’s shock win in 2016, two Jewish men sat down to dinner. Rumours were swirling about Russian interference in the election and it was the idea of a foreign state being able to use computer technology to impact the greatest democracy on earth which led to — six years later — one of the most fascinating and thrilling TV dramas of this year.

Seven-time Bafta winner Peter Kosminksy, who made documentaries before venturing into drama with hits including Wolf Hall, The State and The Promise, was baffled by the idea that a foreign state could have enough silent power to potentially create a seismic shock result.

He started researching it and found a situation even more terrifying; one in which a real cyber war could completely paralyse life as we know it. The idea is explored in his new Channel 4 series, The Undeclared War which he has written, directed and executive produced. The show, he hopes, could be his first continuing series with plans for a second season already in the works.

“When I discover things are going on that I had no idea about, I want to research it — I feel like it’s sort of my job to cast light on things,” he says. “Very quickly as I started researching this, I was shocked by the fragility of our hugely internet dependent society and I wanted people to become more aware of it. The Undeclared War is a cautionary tale; it’s very thoroughly researched — it took five years for us to make.

“I’m not saying this is the way things will turn out but it could. There is nothing in this show that either hasn’t happened or is not being war-gamed by people here and in other countries to try to prepare for this kind of thing. There are no techniques shown or strategies described that aren’t happening.”

The series is a warning from the future. “I think that if we’re not careful, this hot war will escalate to the point where it threatens our civilisation,” he says. “I think it’s that serious. So that’s why I want to tell the story.’

The six-part series, set in 2024 when Britain is about to go to the polls for the election, follows brilliant Muslim coding intern Saara Parvin, played by newcomer Hannah Khalique-Brown, as she starts at GCHQ only to find the cyber team there experiencing their biggest ever threat. A hostile state — thought to be Russia — has managed to paralyse Britain’s computer network.

Planes can’t fly, supermarket shelves are quickly emptied and even the banking system cannot work. The enthralling series has attracted actors including Simon Pegg and Mark Rylance who play GCHQ workers trying to stem the threat and Adrian Lester who stars as the Tory PM — someone who ousted Boris Johnson — and who grows ever more desperate that Britain being paralysed should not impinge on his electoral ambitions.

“As soon as we started talking about it, we saw this was a rich territory for drama,” says Colin Callender, the other person at the dinner and one of the show’s executive producers. “My immediate thought was to do something historical but Peter rightly insisted that it should be something set in the future with the notion being that the new frontier between states is the cyber frontier. And as Peter researched it, with access that only film makers of Peter’s calibre and track record could actually get, all the pieces began to fall into place.”
Kosminsky spoke to dozens of experts both in the UK and America about what a cyber war could look like.

“This was a really lengthy process of research,” he says. “I went into it with an open mind, wanting to see what the research led to. I can’t speak about exactly who many of the people I spoke to are; they spoke to us with an agreement that they will never be attributed and would never have to go on camera, but what they had to tell us was fascinating.”

He also worked closely with cybercrime experts NCC Group who also wrote all the onscreen code that is used in the series. Even malicious code is put in there — although not a code that could be recreated by someone wanting to recreate the pandemonium that happens in the series.

“Every piece of code has been written with its particular function in mind,” adds Kosminsky. “So, we had to be careful to adjust things so that nothing could actually be used to be dangerous.”

He is known for his political work with a left-wing bias — The Promise, his drama about British Mandate Palestine was accused of having an anti-Israel bias — but he insists this series looks simply at the conflict politicians of every hue sometimes have with civil servants. In the series, the Prime Minster instructs GCHQ it should be prepared to strike back — the public is baying for revenge — while they know this will only make things worse.

“There is always a lively conflict between civil servants who have one set of imperatives and politicians, who obviously instruct and command civil servants but often from a different agenda,” he says. “In the series we are dealing with a populist government which is trying to please a constituent base; obviously we are familiar with that phenomenon. But I think it is important to show a conflict between what civil servants think is the right thing to do and what populist politicians might feel is what political necessity dictates.”

Kosminksy has done much of his best-loved work on Channel 4 and this series comes out just as the government is talking about selling-off the publicly owned television channel. He is convinced they are making a huge mistake.

“It feels like cultural vandalism,” he says. “For me, and programme makers like me, Channel 4 is an essential part of the creative firmament. There are shows on the channel that couldn’t be made anywhere else and I think this is one of them. When I made The Promise, it was an extremely difficult, controversial show no other broadcaster would have devoted time and resources to. Or my show The State — about young British Muslims joining ISIS; it is inconceivable that any other broadcaster would have done that.

“For me this proposal is simply to appease a particular base or lobby; there’s no real support for this even from most of the Conservative Party. There isn’t a financial case for it and there will be a catastrophic creative impact if it goes. This is a channel which makes shows for a UK audience — that is our primary motivation. This series is aimed at the British public even if we also hope it will appeal to a worldwide audience because the situation we are exploring in the series affects all of us.”

The Undeclared War will launch on Channel 4 and All 4 on Thursday June 30 at 9pm