Spooks creator reflects on the groundbreaking BBC spy series: 'The fat fryer moment was when we felt we had something special'

"We decided to have the entire show credit-less, so that it felt anonymous and stealth-like," he recalls. "I feel bad about it now, because there were so many people who worked on that show who didn’t get to see their name in the credits – including me, by the way. Not many people know I created the show.

"I think, creatively, it added to the mystique of the show, and was great. On a human level, I wonder whether it was the right choice. But you can never go back. I think it’s part of the identity and the brand of the show that it didn’t have credits."

Having first worked with producers Kudos on Channel 4's Psychos, a drama set in a Glasgow hospital's psychiatric ward starring Douglas Henshall, Wolstencroft began talks with the company about another project, a contemporary spy show influenced by one of his favourite movies, 1965 British espionage film The Ipcress File.

Mirren ("who really was the conceptual heart of the show with me") and Brenton (who "brought a kind of mischief") joined him in the writer's room, with director Bharat Nalluri also becoming a "hugely influential" member of the team (Nalluri is credited with being behind the show's distinctive look and feel, including its use of split-screens and episode-ending freeze-frames).

The ethos behind Spooks in the beginning was, Wolstencroft says, to make a show "about secrecy, not secret agents". "I think that’s why the show was a success, in part, because it was about not just running around and saving the world – but about relatable dilemmas of a high-pressure job.

"You know, Matthew [Macfadyen]’s character, Tom Quinn, meets a woman that he absolutely falls for, but he’s falling for her under a premise, which is that he’s somebody else... That, really, was the beating heart of season one – with all the other bells and whistles that go on top of it. I thought that that was important.

"It was a sort of centre between le Carré and Bond, if I can be bold, [in that] Le Carré is deeply granular behaviour, and Bond is epic, slick, stylish, exciting."

Having worked with Wolstencroft on Psychos, Channel 4 was the first to "show interest" in Spooks, before the show ultimately landed at the BBC – something that the show's creator credits to then-Kudos CEO Jane Featherstone. "For a show this big to get on the BBC, she did a lot of the fighting. You have to fight your way onto a channel for something this ambitious. And bless the BBC, once they got it, they embraced it.

"Gareth Neame, who’s now gone onto great success with Downton, was the commissioner at the BBC at the time and is an unsung hero of the show, because he got it immediately, and supported us."

The first series was "about halfway through" being written when, on 11th September 2001, a series of coordinated terror attacks were carried out against the United States by al-Qaeda, framing the story that Wolstencroft and his team were telling in an entirely new way.

"Suddenly, we’ve got a show that’s like a lens," he says. "That’s telling a story that hasn’t been told before."

Premiering on the 13th of May the following year, Spooks featured two notable British acting talents in Jenny Agutter (a multi-award winning Hollywood veteran) and Peter Firth (Oscar nominated for his role in 1977 film Equus, which also starred Agutter) but was fronted by three rising stars in their mid-to-late twenties: Keeley Hawes and David Oyelowo as junior case officers Zoe Reynolds and Danny Hunter, and Matthew Macfadyen as section chief Tom Quinn (named, as was Firth's character, for Wolstencroft's English teacher Harry Quinn).

"Nobody really knew what would happen, or whether there’d be an appetite," Wolstencroft remembers. "And then we got 9.7 million people for the first episode. Suddenly it was everywhere, and it was thrilling. I was very lucky and very privileged to be able to tell a story that had as wide and supportive a launch as we did."

It was arguably with its second outing, though, that Spooks seared itself onto the national consciousness with an episode which saw the character of Helen Flynn (Lisa Faulkner) brutally tortured and then killed by racist thug Robert Osbourne (Kevin McNally) – scenes which saw first Helen's hand, then her head, forced into a deep fat fryer aired after the 9pm watershed, but drew well over 100 complaints.

"That [idea] came from Simon and I thinking of a sort of worst-case scenario for these characters," Wolstencroft explains. "Together, with Jane, we realised that the best place to do this was not at the end of the series – which is the conventional thing, because you save the best until last, right? – but to put it in episode two, and to fake out the audience.

"Because you have to remember... Matthew Macfadyen, David Oyelowo and Keeley Hawes were not on anybody’s radar in those days. Peter Firth had been nominated for an Oscar – but that was a while ago. Lisa Faulkner was actually the most famous actor in the cast.

"That was the moment, really, that we all felt like: 'OK, we’ve actually really got something special here.' After that, the story goes that every actor, when they got the script for the next episode, would turn to the end to see if they’re still alive. And you can’t want for more than that to create that expectation. Because now it’s alive. Now it’s real.

"When I first came out to Hollywood, I had somebody - who’s now a very famous showrunner - who worked on Alias tell me that JJ Abrams showed that episode to the writer’s room, and he said, 'This is how you create jeopardy.'

"So it became this kind of legendary scene in the industry, and I still get asked about it. If somebody has watched Spooks, they always talk about the fat fryer."

Wolstencroft considers the "fat fryer moment" to be the point at which "the show became the star", allowing Spooks to weather a number of cast changes over the years, welcoming new additions including Miranda Raison (Jo Portman), Hermione Norris (Ros Myers) and Richard Armitage (Lucas North).

"If you lose Idris Elba, it’s not Luther. But Spooks sort of had its own personality. So you could get Adam Carter – Rupert [Penry-Jones]– coming in, and Nicola [Walker, as Ruth Evershed], who’s really my favourite character if I had to pick somebody, who came in the second season.

"Suddenly, season two happens, and you’ve got Harry and Ruth – little inklings of what’s to come. And that sort of became a beating heart for the show right to the end – its tragic end."

Looking back now on the show's beginnings, Wolstencroft "wouldn't say there was anything that was ever a wrong note" – though he admits that an arc planned for Jenny Agutter's character Tessa Phillips, a regular in the first series who went on to make sporadic appearances in the second, didn't quite pan out as planned.

"I wanted her to be a nemesis for Harry... the pitch was: there was a Cold War between departments, right? But we had so many other moving parts in it that we didn’t get to explore that as much as we did. But she's such a stellar actress."

The world we live in today – even before current exceptional circumstances took hold – is a very different one to that in which Spooks first appeared. But while both geopolitics and what we expect from our television drama may have changed, Wolstencroft thinks there's a "very strong argument for bringing the show back".

In some ways, he says, a Spooks revival would have to be very different. "I think we would have a greater racial diversity in the cast. I would want more women writing it and directing it – it was quite a male-heavy show. It’s just the way that everything fell at the time.

"The stories would come from different places, and maybe would be outside London. It would be more distributed across the nation. You would understand more of the world. These characters would perhaps have more different allegiances and different expectations of what the government could do."

To be a success in modern times, though, Wolstencroft believes one thing would have to remain constant – the passion to do something different and push the envelope. "The stakes would be even higher, I would say. I think the mix would be different, and the feel would be different, but the ambition would stay the same – if not greater."

All 10 series of Spooks are available now on BBC iPlayer