What We Did On Our Holiday is written and directed by Guy Jenkin and Andy Hamilton, the pair who created the hit BBC sitcom Outnumbered, and this is like an extended episode of Outnumbered minus anything that made it good in the first instance. This is Outnumbered: The Movie (But Crap). Hard to explain, considering Jenkin and Hamilton have more than proved their worth over the years (they also created the brilliant newsroom satire Drop the Dead Donkey) but we all have our off days, I suppose. And our supremely off days. We must put this down to a supremely off day, particularly as it even has one of those forced, saccharine endings where the violins go mad and everyone’s learnt An Important Life Lesson and hugs on a beach. We may even have to put it down to a disastrously off day, in fact.

This stars David Tennant and Rosamund Pike as Doug and Abi, a married couple taking their three children to Scotland to celebrate the 75th birthday of Doug’s father, Gordy (Billy Connolly), but, unlike Sue and Pete from the TV series, they are not decent if rather incompetent parents simply trying to muddle through with their unruly brood. Instead, Doug and Abi are in the midst of a divorce, but ask the kids to keep it secret as they don’t want to upset Gordy, who has terminal cancer. From this first despicable act — effectively forcing their children to lie for them; nice — Abi and Doug grow no more likable, as all they do is bicker, bicker, bicker, only occasionally pausing for a full-blown fight. They bicker, bicker, bicker and fight in the car, all the way from London to the Highlands. ‘Are we nearly there?’ I wanted to ask. ‘Because I don’t know if I can take much more of this. Tell you what, drop me at the nearest train station, and I’ll see you up there.’

I also wanted to say: ‘Hello? Granddad’s dying here. You’ve said yourselves he’s never going to see another birthday, and also has a weak heart. Might you not wish to show some concern, or perhaps a squeak of upset?’ This film pays no attention to any emotional terrain you or I might recognise, and therefore lacks veracity, depth or a single character to invest in. I think if they had dropped me at the station I’d have headed straight back to London. And changed my phone number. And also my locks.

So, they eventually arrive at their destination (thank God); a country mansion owned by Doug’s pompous, social-climbing brother (Ben Miller), who bullies his wife (Amelia Bullmore) and bullies his teenage son. Might he learn An Important Life Lesson by the end, see the error of his ways, and do hugs on the beach as violins go mad? I couldn’t possibly say. Meanwhile, Gordy is one of those grandpas who only ever exist in the movies. Gordy is a wise sage, but also great fun, always rolling his eyes behind the adults’ backs, introducing the children to the local lesbian, encouraging them to get up to all sorts of mischief and derring-do. He also takes them to the beach where there is An Incident, which the kids have to deal with, and what this film absolutely does not realise is this: the children’s response to This Incident is not funny. It is disturbing. So much of the comedy not only falls flat — bad editing kills most jokes at source — but actually misfires. On one occasion, when Doug and Abi are bickering, bickering, bickering, she threatens to put her head out of the window and shout ‘rape!’ Nice.

Like the sitcom, this is semi-improvised by the children, who do well enough, but their characters are identical to those of the TV children — sensible older one; fighty, hyperactive middle son; youngest daughter who asks too many questions — which immediately puts paid to any sense of freshness. As for the adult actors, they don’t stand a chance against such material, even Billy Connolly, whose character is a cliché and speaks mostly in dull mantras. All in all, this feels like a television Christmas special of something that may never have been up to much. We all have our off days, and our supremely off days, and now I, too, have learned An Important Life Lesson: you can have disastrously off days too.