Mitchell is Stephen, a man who has failed as a husband, a lawyer and at running his late father’s pub. Worse, he’s been usurped in his family’s affections by the charismatic Andrew (Webb), supposedly a former foster child of Stephen’s parents.

“I like to pay the comic mattress on which people jump up and down – there’s a lot of comedy and fun acting to be had from the character that things are happening to,” said Mitchell.

He described Stephen as “disappointed and self-loathing and endlessly self-doubting, also intelligent and little bit angry.”

The character, Mitchell said, perhaps not entirely seriously, was based on no-one other than himself: “What he looked and sounded like was inspired by me… They gave me other clothes to wear that some people have been good enough to say are sometimes distinguishable from the sort of things I wear anyway.”

“David and I try not to look into it too deeply as to what it is about our personalities that makes writers come up with people like this for us to play,” said Webb.

There are similarities to both actor’s characters in Peep Show, the long-running Channel 4 sitcom created by Sam Bain and Jesse Armstrong, for which Blackwell also wrote.

“Andrew’s a liar. So is [Peep Show’s] Jeremy but Jeremy was an idiot, whereas Andrew is a better liar… He goes around telling these whoppers. So he’s either this very needy person who is so desperate for approval that he will say potentially quite dangerous things or he’s an absolute maniac. I never really decided during series 1 or 2. I’m not sure if Simon’s decided; certainly the character doesn’t know what he’s doing. It’s like Blair, he believes it while he’s saying it.”

The comic actors were talking at an RTS event shortly before the start of series two.

The first series ended with Stephen strung out on pills and booze, and Andrew running the pub, loved by all. “It seemed to be a nice way to finish it with Stephen catatonic in a chair… driven to the edge of his sanity,” said Blackwell.

In series 2, Andrew’s true character remains uncertain. “Once you know for sure whether he is this guy coming back to a family where he was very happy or he’s Satan… you let the air out of the set-up,” added the writer.

But Blackwell promised some changes. “In series two, the roles are reversed: Stephen’s been away having some kind of treatment. He comes back and Andrew is the boring, mundane one [working] in the pub, and suddenly Stephen feels that he’s the exotic one coming back having spent some time away in therapy. We thought that was a nice mirror to the first series.”

Viewers have waited longer than planned for a second outing of Back. In autumn 2019, shortly before filming was due to start, the two leads had insurance medicals.

“Normally it’s very perfunctory and the doctor just makes you cough. This time, he put a stethoscope on my heart and pulled a face and said, ‘Oh dear, what have you been doing about the heart murmur?’ And I said, ‘What heart murmur?’” recalled Webb.

“A couple of days later, I had a cardiologist tell me I had a mitral valve prolapse, and that it wasn’t something that could be fixed with drugs and that I needed surgery; otherwise, the heart was going to fail in the next two to six months. That was a bit of a shocker.”

Webb completed the first week of filming and then had the operation. Production continued for as long as possible, shooting around scenes with Webb’s character.

It resumed when Webb had fully recuperated, until the pandemic brought filming to a shuddering halt. Finally, the show wrapped in autumn 2020.

“The continuity is pretty funny on my face.… you’ve got someone who is clearly very, very ill … and then you’ve got someone who is not ill anymore but pretty knackered, and then finally someone who is, [points at his face] whatever you think of this face. It tickles me to watch that.”

“Back preview and Q&A” was held on 20 January, chaired by the journalist Caroline Frost, and produced by the RTS and IJPR. A longer report will appear in the February issue of Television.

Watch the event in full below.