Of course, in real life, such people are incredibly rare.”It all stems from the fact that every woman on American TV looks like a stripper – Pamela Anderson has a lot to answer for. “Old people just aren’t sexy to TV companies,” observes Flemyng. “Every commissioning editor wants every programme to have a sexy, Hollyoaks-type ethos – every single person in the script has to look like a 19-year-old blonde beauty. TV execs, advertising gurus and certain newspaper editors fetishise the young and seem to reside in a Logan’s Run-style universe where anyone over 30 simply does not exist.Such execs are shaking hands with their dearest friend: rampant ageism. So much TV these days is so safe – at least this drama is trying to push the boundaries a bit.”But just why, in an age when people seem quite happy to let it all hang out while discussing their libidos on Trisha or The Jerry Springer Show, is the sex life of the older generation still such a touchy subject? Flemyng reckons that we have been conditioned by the media to believe that only young, firm flesh can be attractive.

“It will shock some people, because it’s a part of life that most of us haven’t addressed. But there again, I’ve always enjoyed offending people,” adds the actor, who began his career in radical theatre working with writers such as Snoo Wilson. “When I started out, I only thought a play was a success if people left before the end – that was the point of theatre! We weren’t doing our jobs properly if all the audience were still there at the end! In all art, you should always try to offend people, because that’s how you make them think. Old people bonk – it’s official.”But won’t the drama’s frank portrayal of wrinkly sex upset some of BBC2’s more genteel viewers? Freeman certainly hopes so.

“People are nervous about the thought of anyone over Cameron Diaz’s age being sexually active. For that reason, When I’m 64 is great!” beams the 37-year-old actor, a fixture in Guy Ritchie’s “geezer chic” diptych, Lock, Stock and Two Smoking Barrels and Snatch.Flemyng momentarily turns a whiter shade of pale as he recalls what for him was a most unsavoury encounter with overage sex. “I remember going to visit an ex whose parents were well into their sixties. One morning, we caught them in a compromising position, and I was absolutely horrified! That’s not what we’re used to at all But this film might help overcome those prejudices.

He’s seeking enlightenment, but as far as his kids are concerned, it’s: ‘What are you doing? That’s no way to behave in front of the grandchildren!’”Flemyng extends the concept and suggests that those not yet collecting bus passes are repelled by the image of anyone of a pensionable age doing anything more racy in bed than reading Saga magazine. They don’t understand that their father could have a change of heart and search for something deeper and more spiritually nourishing. “Kids never want to hear about their parents having sex,” he says. “They find the whole idea utterly disgusting!”Outhwaite is stretching out at the back of the catering-bus, next to a display of “all new garden sheds at knockdown prices”. She is glad of a break between gruelling scenes in which Ray and his two censorious children fall out at what is supposed to be a happy-families barbecue. Done up in her character’s costume of denim jacket and matching skirt, she points out that the bigotry of people such as Caz and Little Ray in When I’m 64 is not uncommon.According to Outhwaite, 33, “Their outlook is quite suburban and narrow-minded Their attitude toward their father is based on ignorance It’s a story about people who can’t cope with change.