W1A actor Jason Watkins to star in new ITV drama as the landlord falsely accused of Joanna Yeates' murder

Jason Watkins has been a steady supporting actor for most of his career. But now, following a family tragedy, he's set to play the lead role in The Lost Honour of Christopher Jefferies

Watkins says: 'I've done something like 80 different shows. They tend to be supporting characters so I don't tend to get the publicity spotlight thrust on me' (David Vintiner)

I'd been wanting to interview the actor Jason Watkins for a long time. He pops up all over the place, his perkily distinctive presence enlivening shows as varied (in quality, as well as subject matter) as BBC3's vampire drama Being Human, Sky 1's supermarket sitcom Trollied, and BBC2's in-house satire W1A, as well as a movie repertoire which includes Tomorrow Never Dies and the nearest thing that contemporary British cinema has to the Norman Wisdom films of yore, the Nativity! series of seasonal comedies (Nativity 3: Dude, Where's My Donkey?! is currently showing in the nation's multiplexes).

But when it comes to profile interviews, the trouble with Watkins is that he invariably appears in supporting roles – and although I once discussed with an editor the idea of a feature along the lines of 'Great supporting actors of our time', their agents weren't ecstatic about their clients being so typecast. After all, today's supporting actor is tomorrow's leading man – in theory, anyway.

"I've done something like 80 different shows and a few films along the way," says Watkins when we finally do get to meet. "They tend to be supporting characters so I don't tend to get the publicity spotlight thrust on me." He adds quickly, however, that that is how he quite likes it – head below the parapet and all that – but that "I've never had a big editorial spread... so this is quite nice".

The opportunity arises because Watkins has finally, two years after his 50th birthday, landed a lead role – and a particularly juicy one at that. He is playing the title character in The Lost Honour of Christopher Jefferies, ITV's real-life drama about the retired Bristol teacher who was arrested in late 2010 for the murder of his young female lodger Joanna Yeates, and saw his character traduced by the tabloid press in an insinuating barrage of libel – simply because he lived alone, had eccentrically unkempt hair and a somewhat high-handed, school-masterly manner – with the hacks door-steeping his home in Clifton. Joanna Yeates's neighbour and another of Jefferies' tenants, Dutch engineer Vincent Tabak, subsequently confessed to her murder, and was charged and convicted.

The two-part drama is written by Peter Morgan, that gifted chronicler of remarkable lives (Longford, The Queen, Frost/Nixon) and directed by Roger Michell (Notting Hill, The Mother), who was actually taught by Jefferies while a pupil at Clifton College. "Christopher started a film club and Roger attended that," says Watkins. "He's one of many, many people who have been taught by him [Jefferies], the best man at my wedding being one of them; in fact, you go to a party in north London and somebody will have been taught by him.

"Roger thought there was absolutely no way that Christopher would be capable of such a thing and was appalled by all the betrayal in the press – the seeming betrayal of what former pupils were supposed to have said about him, for example... very hurtful things that are dealt with in the film."

Watkins's Jefferies speaks rather like Brian Sewell, has strange exaggerated hand movements and, of course, that long, combed-forward sweep of white hair that has since been coloured and cut short, following the former teacher's decision to give evidence to the Leveson Inquiry and become a public speaker on the matter.

"I went off and looked at all the footage that I was able to find," says Watkins of creating his version of Jefferies. "Footage of Leveson and of him coming out of his house and being door-stepped. I have to say I was resistant to meeting him because I thought I had sort of got him, in terms of impersonating him and applying that to the script. But Roger persuaded me and we drove down to Bristol and I spent some time with him on my own in a café – and spent a lot of time looking at him while pretending to listen to what he said. He caught me out a couple of times which was kind of embarrassing... he gave me one of his withering looks.

"He's a formidable person to meet. He's extremely eloquent and he's school-masterly still –and – I suppose I'm revealing my own insecurities about my own education but, I mean, one feels one needs to use the right tenses when speaking to him. Roger Michell, who had of course been taught by him, started being intimidated by me playing Christopher."

Watkins as Christopher Jefferies in Peter Morgan's ITV drama (Carnival Film & Television Ltd) (Carnival Film & Television Ltd)

What did Watkins learn from watching rather than listening to Jefferies? "He did one particularly unusual thing with his hands behind his neck... it was really uncomfortable and he'd hold that for a very long time. And his nails are longer than most people's nails and he does care for them, and I asked him why he kept his nails so long. And he went 'Are they'?

"Trying to build his accent was interesting. His background... I mean his father is from Immingham [in Lincolnshire] and managed a power station, he was then moved to Northampton and schooled in the Wirral... it's a right old mix. My accent... my father's from Cleethorpes and my mother's from Manchester and I was born in the Midlands and brought up in London, so I've got an element of that."

Watkins's mother, Avis, was a teacher and his father, Alan, a metallurgist who is supposed to be related to Jane Austen somewhere along the line, although he was adopted at birth and Watkins doesn't know too much about the paternal side of the family. Alan Watkins managed to get into Cambridge, however, an academic prowess not inherited by his son, who (partly due to his then undiagnosed dyslexia) achieved "rubbish O-levels" and not enough to pursue his intended career as a PE teacher. He was good at sport as a teenager, and naturally gymnastic.

"Freakishly I used to be able to run on my hands when I was a kid," he says. "I got quite close to the world record, when I was about 12 or 13, of running the length of a basketball court on my hands... I got to within a couple of seconds." Can he still do it? "Yes, it's my party piece sometimes; you can watch on the DVD extras for Trollied Series 1." Trollied, in which Watkins plays a mild-mannered supermarket manager, is all right, on a quiet night, but the promise of the sight of Watkins walking on his hands is still not quite enough reason to buy the box-set.

Anyway, two inspirational drama teachers at his Hounslow comprehensive – plus the ability to do impressions of his fellow players on a youth cricket team in Isleworth, west London (whither the Watkins family had migrated when Jason was eight) – led him to eventually apply to Rada, and be accepted at the same time as Ralph Fiennes, Iain Glen, Jane Horrocks, Imogen Stubbs and Neil Dudgeon. "It was a good year," he says, adding that such a wealth of talent somewhat intimidated him. "Perhaps, thinking back, I felt like a little boy from the suburbs.

"I didn't have a plan... I didn't have a burning ambition. I mean, I remember a teacher asking us, 'What do you want to do?' and I think somebody said, 'I want to go and do films in America' and somebody else said, 'I want to work in the RSC and play all the kings'. I was just happy to work."

And work he has. In the last two years alone he has appeared in Call the Midwife, Doctor Who, The Wrong Mans, Atlantis, W1A, Our Zoo and Trollied, as well as filming the Christopher Jefferies drama in Bristol, and playing the Duke of Suffolk in the upcoming Hollow Crown, the BBC Shakespeare trilogy that will also be giving us Benedict Cumberbatch's Richard III. "I like playing characters other than myself," says Watkins. "As Kate Bush said when people asked her, 'Why do you invent these characters in your songs?' and she's says they're a lot more interesting than I am. Maybe part of me feels a bit like that."

My favourite of his recent roles has been as W1A's Simon Harwood, the slippery 'Director of Strategic Governance' at the BBC, a nebulous position which seems to consist entirely of sitting in meetings and relaying the latest thoughts of 'Tony' (BBC director general Tony Hall). "A lot of people in the BBC say, 'I know him... he's based on my boss'," says Watkins of a character well described by one TV critic as "an affable sociopath". Was he based on anyone, at the BBC or elsewhere?

"I didn't actually have a strong individual in mind; the script is so good... the rhythms... none of it is improvised at all. The 'ums' and 'ers' are all down there... everything is on the page. A voice came immediately and I thought I don't need to go too much deeper."

Watkins has four children from two marriages – two teenage boys, Pip and Freddie, with actress Caroline Harding (who is now married to Chris Gascoyne, the Coronation Street actor who plays Peter Barlow) and a son and a daughter with his second wife, the jewellery designer Clara Francis. The couple experienced the unimaginable horror of losing another daughter, Maude, during a winter flu outbreak in 2010/2011. The two-year-old developed sepsis – an often deadly bodily response to infection – and they discovered her dead in her cot on New Year's Day.

"It is the thing that's ever present in our lives now... the trauma that we've had," says Watkins, choosing his words with care. "It's good to talk about it in this context, this sort of interview, mainly because we received a lot of comfort from people who'd been through what we'd been through.

"Maude died on New Year's Day in 2011, which was a week after the events in Bristol. Sharing the headlines with Christopher was a flu epidemic that my daughter died of a week later. So it's a strange, strange world... there are all sorts of strange coincidences while we were filming it of what I was doing on that day... Christopher was being interviewed by the police, and we were going through the trauma of discovering that Maude had died in the night.

"I hope it's not too convenient an association to make but I understand what it's like to go through a terrible life-changing trauma like Christopher has been through, but we also know what it's like to lose a daughter, albeit in very different circumstances to what happened to Joanna [Yeates] and her family."

Watkins is part of Slow (Surviving the Loss of Your World) a group in north London run by bereaved parents for bereaved parents. "Meeting people who had been through such a terrible event was a great comfort, so me talking about it now will hopefully enable people going through what we did to understand that there are people who have been though it and survived."

As for Christopher Jefferies, despite vindication in the libel courts and the new-found purpose as scourge of the more irresponsible wing of the tabloid press, there is a sense that he may never shake off his wrongfully tarnished reputation. Mud sticks. "When we were filming in the middle of Clifton, there were a couple of council workers working on a low wall there, and they asked what we were filming. When we said we doing a thing about Christopher Jefferies, they said, 'Oh, yeah, he's the bloke that killed his tenant, isn't he?'

"Christopher has said it's something that will stay with him for the rest of his life. As he goes about his business he'll always be thinking that there are some people who'll be thinking, 'There's that bloke who...' . To have that feeling imposed on you, having been wholly innocent, is a very difficult thing to have to deal with. The film is a chance for Christopher to have his story stated in as public a way as possible"

'The Lost Honour of Christopher Jefferies' begins on ITV on Wednesday at 9pm