Watching veteran actors Sir David Jason and Stephanie Cole seamlessly deliver their lines in Still Open All Hours, it’s hard to believe that these giants of television are only seconds from collapsing in giggles. 

But it’s true, according to Stephanie Cole, who has played the sitcom’s randy widow, Delphine Featherstone, since the show’s third series in 1982.

Even as a septuagenarian, Delphine remains as hot for David’s Granville Arkwright as she once was for his uncle, Albert (Ronnie Barker), and she’s constantly propositioning him – her come-ons are some of the funniest lines in Roy Clarke’s sitcom. 

“We’re terrible,” says Stephanie, 76, about giggling with her co-star.

“I look at David and I can see this twinkle behind his eye, and I keep myself together, but he sees a twinkle in mine and then we just go. Laughter is very close to the surface.

“It’s the same for me with Geoffrey Whitehead, who plays Mr Newbold. We all spend an awful lot of the time crying with laughter.”

David concurs about the jolly atmosphere on set.

“It is always hard work, long hours and a lot of dialogue on a weekly basis, but we all get on so well and have so much fun, it makes it all worthwhile,” says the 77-year-old star.  

It’s heartening to know that the actors get on as famously behind the camera as they squabble in front of it, when this week’s Christmas episode kicks off the fourth series of the rebooted sitcom. It has been enormously popular since its revival in 2013.

In the festive episode, skinflint shopkeeper Granville is horrified to discover that his regular customers are planning to leave town for the holidays.

Not only will it mean takings are down and his beloved Mavis (Maggie Ollerenshaw) will be absent, whisked away by Madge (Brigit Forsyth), but when he learns that Mr Newbold is planning on doing a runner, he realises it would leave no buffer zone between himself and the amorous intentions of Delphine.

“She is terrifying,” laughs Stephanie.

“She does pursue him like a mad dragon, really, and she’s so blatant sometimes.”

Stephanie has played Delphine off and on for 35 years after Ronnie Barker chose her for the part. They came across each other in a building of rehearsal rooms in west London, when she was rehearsing Tenko, the 1981-84 prisoner-of-war drama, and he was doing Open All Hours. 

“You never knew who you’d get into the lift with to go to the canteen,” recalls Stephanie.

“One day it could be Tommy Cooper, the next John Gielgud. 

“So I got into the lift and it was Ronnie Barker. He was kind about Tenko, which had just started, and a few days later my agent rang me and said, ‘He’d like you to take over the part of the Black Widow – would you like to?’ Well, of course I would!

“I was incredibly lucky, because it meant I was doing roles in drama and comedy, which very rarely happens. And watching Ronnie and David work together, you could learn so much – it was like a masterclass,” she recalls.

Other characters also back are Granville’s son, Leroy (James Baxter), bickering couple Eric and Kath (Johnny Vegas and Sally Lindsay), Cyril (Kulvinder Ghir), Mrs Hussein (Nina Wadia) and Gastric (Tim Healy). 

David Jason expresses his gratitude that, Roy Clarke – now 87 – is still producing great scripts. 

“Watching Still Open All Hours is a little step into a barmy world of escapism,” he says.

“With all the troubles in the world today, Arkwright’s is a little pot of fun, surrealism and postcard humour.” 

Still Open All Hours, Thursday 28th,7.30pm, BBC1