SOAP star John McArdle is going full circle.

Best known as the long-suffering Billy Corkhill in Brookside and Ronnie Hale in Emmerdale, the Liverpudlian actually started his acting career treading the boards in physical theatre.

And after stints in the landmark northern soaps, along with parts in Mersey Beat, New Tricks, Waterloo Road, Prime Suspect 5, Waking the Dead, Law and Order UK, Casualty and Holby City, he is once again being put through his paces in a masterpiece of dynamic stagecraft.

Things I Know To be True, which opens at the Oxford Playhouse on Wednesday, is the story of a family disintegrating in the face of dark revelations. And at the heart of it all is Bob – a dad, and long-suffering ‘everyman’ played by 68-year-old John.

“Things are wonderful,” he says, taking a break from rehearsals.

“No actor worth their salt could refuse to do this even though there are challenges when it comes to the physical side of it.

“In rehearsals we do warm-ups for an hour before getting into the physical stuff, so I do have to be fit!”

He goes on: “People know me mainly from my television stuff, which I loved doing, but I have done a lot of theatre and started in the 80s in a physical theatre company. I am not a stranger to it, though I haven’t done anything like this for a long time.”

The production is staged by the appropriately-named Frantic Assembly, and returns to the Oxford Playhouse after a successful run last year albeit with a largely new cast.

Touching, funny, and a little unsettling, Things I Know To Be True introduces us to what appears to be an average family living in the suburbs of the Australian city of Adelaide.

Bob and his wife Fran have worked hard for their children, with Bob now spending his time tending his beloved rose bushes in the garden, however, his life is rocked when home truths emerge about those closest to him.

Staging is gracefully and poetic, characters plucked into the air by the rest of the cast to be lifted over heads and deftly deposited.

“The script would stand alone without the physical element, but it does enhance the beauty of it,” says John. “It’s a spectacle and is very different from television.”

He is delighted, though, that his fame as a soap star is attracting audience members who might not traditionally have bought theatre tickets.

“People turn up who have never been to the theatre before,” he says.

“I don’t just want to preach to the converted, but to bring new people all the time. That includes Oxford, which is obviously not just the University, but also has a big working class, so it is great.”

And he identifies with first-time theatre-goers. “I didn’t go to the theatre until I was 23, and then went to drama school when I was 24,” he says.

And he says this is a great show to start with.

“Apart from the obvious Shakespeare and Miller, there’s only one other play I’ve really rated: Two by Jim Cartwright, and this is on that level. I really enjoy it.”

Two saw him starring alongside fellow Brookside actor Sue Johnston, who later when on to find fame as Barbara Royle in The Royle Family alongside another ‘Brookie’ star Ricky Tomlinson.

Though, he says, appearing on stage could not be more different to TV. “This is more gruelling,” he says. “Emmerdale is patched up and you have to learn quickly. It was a wonderful place to work and I loved every minute, but it’s a bit like a sausage factory. This is harder and more satisfying.

“But then I don’t watch soaps; I prefer Scandi noir.”

That said, he is immensely proud of Brookside, which was first aired on the launch night of Channel 4 in 1982, running for 21 years. The series was groundbreaking in its approach to social issues, echoing the politicised culture of the 1980s and tackling hard social issues – not least Billy Corkhill’s redundancy, unemployment and marital breakdown.

“It was grittier,” he says. “We had a single camera and fantastic writers such as Jimmy McGovern and Frank Cottrell-Boyce as well as Phil Redmond. It created a lot of good actors like Ricky Tomlinson and Anna Friel, but also crew and directors.

“It was a young person’s programme because of the humour, and was real fun. And it was realistic, unlike Coronation Street. Nobody lives in those streets anymore, but Brookside was on a new estate with a mix of working class and upper working class people. It was very real.”

And while Adelaide is a long way from gritty Liverpool, there are echoes of Billy Corkhill in Bob.

“Bob worked in a factory, gets made redundant, like Billy, and is dumped in his garden.

“He is older than Billy and loves his garden and family but gets fed up with it all when the truths begin to come out – which they do...”

* Things I Know To be True is at the Oxford Playhouse from Wednesday to next Saturday. Tickets from oxfordplayhouse.com