Two Doors Down, review: this sitcom just isn't the same without Doon Mackichan

There is no harder comedy to review than Two Doors Down (BBC Two) because nothing happens, everything stays the same, the characters all behave exactly as you would expect and the jokes couldn’t be more signposted if they were printed on billboards.

Or at least that was the form for five series. Series six, however, which began last night, opened with a bombshell: Cathy, played by Doon Mackichan, has left Colin for an estate agent in Sharm El Sheikh. This cast change, prompted by Mackichan upping sticks for reasons unknown, gave Two Doors Down an opportunity as well as a problem.

The opportunity was to give the ever-excellent Jonathan Watson, who plays Cathy’s hapless husband Colin, something to work with. He didn’t disappoint, appearing on the doorstep with half a takeaway down his front and slowly admitting that he hadn’t left the house since Cathy’s elopement. Down-in-the-mouth Colin was a delight as he basically ceased to function, leading to one superb scene where Beth (Arabella Weir) tried to show him how to make macaroni cheese, and Colin stood dumbstruck as if she was conjugating Swahili.

The problem, slightly predictably, was that Doon Mackichan was the funniest thing in Two Doors Down – without her it lagged horribly (and I have to say that even with her it was never the peppiest of sitcoms). Credit should go to the writers, Simon Carlyle and Gregor Sharp, for confronting the elephant in the room, as well as the cast, who as ever made a lot out of not much: practically the whole of the episode consisted of Beth, Eric (Alex Norton), Gordon (Kieran Hodgson) and Ian (Jamie Quinn) talking about Cathy, with no-filter battleaxe Christine (Elaine C Smith) chipping in with her usual delicacies (“So, is she away with somebody else or has she just had enough?”).

But Two Doors Down relied on Cathy for incident, visual humour and punchlines. She was the show’s Dorien Green (if you’re a Birds of a Feather fan) or Kramer (if Seinfeld, another show about nothing, is more your bag). It’s fine to remove her for a single episode in which her absence remains the main story, but for the balance of the show – for the jokes, frankly – she needs replacing, fast.