With a brand new series of Not Going Out marking 20 years of the record breaking show, the BBC is celebrating the occasion with this documentary charting the history of Lee Mack's sitcom.

And there is plenty in the story to cram into a thirty-minute overview. Lots of stuff here I think I knew but also lots of bits that are new to me. I knew, for example that it emerged from Lee Mack's Edinburgh Fringe show with Catherine Tate and Dan Antopolski, but I don't think I've ever seen a clip from the unaired pilot featuring Mack and Tate - it was decided that they didn't seem right as a couple, hence the idea of the landlady and tenant.

Then there was Lee's American landlady in the early days played by Megan Dodds, because Lee loved US sitcoms so much. Then gradually the show started to find its feet. Only to be cancelled. But a petition and people power – or incriminating pictures of BBC execs, jokes Lee – got it revived and it has never looked back.

We hear from co-writer Daniel Peak and get a peak at rehearsals that maybe hint at one of the secrets of its success. Unlike many sitcoms the script gets a live reading in a theatre in front of a real audience so that Mack and the team can see what works and what doesn't, with the emphasis always on the funny. Too much drama would make it a comedy drama and Mack says he doesn't want to do that. He clearly loves the trad format, wondering why people slag of seventies comedies when there were so many great seventies comedies.

And he is also not afraid to take risks, doing a live episode which broke the fourth wall. He even talked about a whole series of live episodes. Instead, to the production team's relief, they did episodes in real time which were more like mini-plays.

We also get to hear from his co-stars, including Sally Bretton, Tim Vine, Hugh Dennis and Abigail Cruttenden, as well see the series evolve, with characters leaving and new ones, such as Katy Wix, joining. Miranda Hart was in it for a while until she landed her own sitcom and couldn't do both. In fact Hart was in it twice. Before playing the cleaner she played an acupuncturist. But Mack thought she was the best person for the part of the cleaner, let's ignore the fact that she's already played someone else.

At the end of the doc Mack wonders if he'll still be doing Not Going Out in another twenty years when he's 77. He says if you'd asked him when he was 37 if he would be doing it at 57 he'd have laughed at you, but here he is, so who knows? Maybe it'll be Not Going Out of the care home. 

A great curtain raiser for the new series. I'm only surprised that, given Mack's love of a conceptual idea, this documentary wasn't twenty minutes long. One minute for each year of the sitcom.

20 Years Of Not Going Out, 9pm, BBC One and also on iPlayer

Picture Credit: BBC/Avalon/Perou