When Kit Harington was a schoolboy in Martley, Worcester, in the late ’90s, he liked to tell friends the truth about Bonfire Night. It wasn’t Guy Fawkes, he’d say, who was the brains behind the Gunpowder Plot of 1605. It was a devout Catholic from Warwickshire called Robert Catesby.

He was the one who devised the plan to blow up Parliament, wipe out King James I and, in so doing, the ruling Protestant elite. Guy Fawkes was just one of the plotters. The question of why Fawkes is etched into the mythology of 5 November, and not Robert Catesby, is a personal one for Harington: he is a distant relative.

‘My middle name is Catesby and it’s something I was proud of,’ he says. ‘It’s a part of my family history.’

Harington went on to find fame as Jon Snow in the HBO series Game of Thrones (where he also met fiancée Rose Leslie; the couple announced their engagement last month). But he never forgot his relative. And now, more than 400 years after his death, Harington has, in his own way, led a campaign to ensure that we don’t either.

Gunpowder is a three-part BBC One drama developed by Harington (he also plays Catesby), written by Ronan Bennett (the screenwriter and novelist best known for TV crime-drama series Top Boy) and directed by J Blakeson (The Disappearance of Alice Creed).

It tells the story behind the Gunpowder Plot from the point of view of the disaffected Catholics. While Catesby is not exactly accorded glory (he was a terrorist; his group ‘the al-Qaeda of the 16th century’, according to one commentator), the drama does make it clear how despicably Catholics were treated in England in the early 1600s.

The first episode begins with mass in a stately home – a perilous act of worship at that time. Hopes of greater religious tolerance under the new King James I have faded. And England has become increasingly hostile, not just to the Catholic faith, but to Catholics’ very existence.

They are imprisoned, fined, harassed; priests are hunted down, tortured and executed. And the drama unflinchingly recounts some of the gruesome execution methods used for those who are caught.

We watch a young lay priest, clad only in a loincloth, being hanged and then cut down while still alive; whereupon he has his bowels removed, then is beheaded and divided into four pieces (hung, drawn and quartered). Such is the punishment that awaits you, as a Catholic of that period, when you refuse to renounce your beliefs.

But rather than being crushed by the threat of such a death, Catesby rallies a Catholic community (including his cousin Anne Vaux, played by Liv Tyler) that defiantly continues to worship in secret, often in back rooms, after dark.

The idea, says Harington, grew out of a conversation with his friend and housemate Daniel West (the two met at drama school) about three years ago. ‘We were sat in a pub having a drink and I said to Dan, “I don’t know why no one has done the story of Catesby,”’ he recalls. The two got very excited. ‘And when we woke up the next morning we still thought it was a good idea,’ says West.

They wrote a treatment and contacted production companies. The series was commissioned as a partnership between Thriker Films (Harington and West’s company) and Kudos, the drama production company.

There have been other incarnations, for example, Gunpowder, Treason & Plot, a 2004 two-part TV drama by Jimmy McGovern with Michael Fassbender as Guy Fawkes, which addressed the life of Mary Queen of Scots and her son James I.

‘But there hasn’t been a drama that really seeks to understand what drove those men to try and carry out that act,’ says executive producer Ollie Madden, who first met Harington on another Kudos production, Spooks: The Greater Good (2015).

For anyone attempting to dramatise the Gunpowder Plot there are two major drawbacks: first, there is no hero. And, second, everybody knows how it ends. But, thanks to Bennett’s decision to flesh out the characters and focus on the efforts of the authorities – headed by Robert Cecil (Mark Gatiss), King James’ spymaster-in-chief – to catch the plotters, it is hoped that the audience will be more invested.

‘Catesby has lost a wife and a child by the time we meet him. He’s got a very fractured and difficult relationship with his surviving son and he’s a man who feels like he’s got nowhere left to turn,’ says West, who worked with Bennett on the script and also plays Thomas Percy, one of the conspirators. It’s like in Titanic, says J Blakeson, ‘By the time you get to the end, you are so into the characters’ stories that when it happens you are almost surprised.’

You can understand Bennett’s interest: he was born in 1956 and raised in Belfast by a Catholic mother, and came of age at the height of the Troubles (he was wrongly convicted of murdering an RUC officer and spent 18 months in Long Kesh prison, later renamed the Maze).

This and other aspects of his life, such as spending 20 months on remand in his 20s, after becoming involved with the anarchists in London, means that politics runs through his work. ‘Ronan has said he wanted people to think about what happens when you persecute a religious minority – they come back to bite you,’ says Madden.

The drama is neither pro-Catholic nor pro-Protestant. It’s about what people will do for their families. It’s about how far we will go in the service of beliefs and the narratives we tell ourselves to justify what we have done. And there is, of course, a clear reason why producers are interested in telling this story now.

‘In no way are we condoning the terrorist actions these men tried to carry out,’ says Madden. ‘But we do think there is a contemporary resonance in trying to understand what leads desperate people to try to do that kind of thing.’

Tuesday, 11 April: a backlot near Dalton Mills, Keighley, West Yorkshire. Kit Harington is complaining of an itchy beard. Unlike most of the whiskers on set (and the 17th century was rich in beards), Harington’s are real. In fact, Harington as Catesby looks exactly like Harington as Jon Snow, bar an upward curve to his moustache (a period detail achieved with copious amounts of wax).

‘I would have loved it if Catesby had had short hair,’ says Harington, who speaks of wanting to try a different look from the one he’s had in Games of Thrones for the past six years. ‘But he didn’t. He had long hair and a beard, so I wasn’t going to fight against it.

‘I love my character in Game of Thrones,’ he continues, ‘but he’s a pretty solid person and I wanted to do something a bit different from that. Catesby is someone who is doing something really, really bad, but he thinks it’s right and there’s a fanaticism to that, which I enjoy.’

With his role as co-executive producer and the ‘face’ of Gunpowder, Harington has broken new ground. ‘I’ve turned to Dan at times when we’ve both been on the back of a horse and we’ve whispered to each other, “We’re making a TV show!” Whatever happens to this piece, I am really proud that we’ve got it on telly.’

Liv Tyler isn’t an actress you associate with a British period drama. She first showcased her English accent in Onegin (1999), and again when playing Arwen, an elven princess in the Lord of the Rings trilogy (2001-03). ‘I moved to London last August,’ she explains, when we meet in a break between filming. Her partner, Dave Gardner, a sports agent, is British.

They have two children together, Sailor, two, and Lula, 15 months. (Tyler also has an older son, Milo, 12, from an earlier marriage.) ‘And I was getting excited to be in London, then this came up and it was exactly what I needed. A perfect amount of work, a lot of substance and something that interested me. As an American I don’t know very much about Bonfire Night, but I also don’t think English people know that much about it either.’

As Anne Vaux, Tyler’s beauty is hidden under a bonnet, ruff, collar, corset and farthingale (hoop skirt). She has an austere central parting in her hair. But she has been most challenged by the set: about 75 per cent of the eight-week shoot has been in Dalton Mills, an abandoned textile mill.

Plus there have been many tons of fake mud imported to capture the filth of 17th-century London. She says the ‘scuttling creatures’ living in the mill included feral cats.

‘We’re all sick,’ says Tyler. She coughs. ‘That is my mud cough.’

For Grant Montgomery, the production designer, the mill is perfect. He first discovered it three years ago when he worked on Peaky Blinders. ‘It’s got this incredible scale and you can graft things into it,’ he explains. Which is much needed, as Gunpowder aspires to be cinematic and features multiple locations.

‘We’ve created 100-plus sets in the mill,’ says Montgomery. Everything from the Duck and Drake tavern to the Queen’s chamber; even Belgium and Spain.

‘He uses the mill like a big Lego set,’ says Blakeson. ‘He’ll build something, take it to pieces and then build something entirely different, but with the same pieces.’

When I leave, the team are shooting the scene where Guy Fawkes (Tom Cullen) first appears at the end of the first episode. ‘It’s quite bold to do a third of a drama about the Gunpowder Plot without showing Guy Fawkes,’ Blakeson admits. ‘When he does finally appear, in a dark alley, you get this chill on the back of your neck… Ah, here we go.’ [Source]