Boxing Day’s viewing: The Royal Bodyguard, BBC1 The Borrowers, BBC1

I realised that The Royal Bodyguard despised me about five or six minutes in. Mark Bussell and Justin Sbresni's new comedy began with a backstory prologue to introduce us to its central character, Guy Hubble, a blazered ex-military jobsworth who has a job supervising the Buckingham Palace car park.

As the Royal Household wait for the Queen to climb into the royal coach, Hubble spots a stray crisp packet on the gravel and leaps forward to spare Her Majesty this distressing sight. And then, seeing that one of the Coldstream Guards is asleep at his post, he inflates the bag and pops it in his face, with a bang like a pistol going off. The coach horses bolt, with the Sovereign dangling from the steps. Having set this disaster in motion, Hubble then puts things rights, seconds away from a crash that would have put Prince Charles on the throne. How did this idiot get a senior post as a royal bodyguard?That's how.

It's not really a complicated comic idea, this. Think Inspector Clouseau and you're halfway there. Hubble, played by David Jason with a bantam-strut of self-regard, is chaos in trousers. But just in case we're a little slow on the uptake, the writers supply an exasperated superior to underline things for us. And then he finishes his little speech with the ponderous line: "With him in that job... anything could happen." Well, thank you for the clarification, but I'd actually worked that out five minutes ago. The character's the idiot, not the viewer. What followed was, as they say, "predictably hilarious", which means not terribly hilarious at all, unless you have a thing about seeing David Jason in his underwear hanging off a balcony. Nothing wrong with a cartoon, of course, but all too often this one is crudely drawn.

Clashing with a pair of sinister Slav assassins who talked about "shaking the vurld to its core", Hubble managed to cock everything up until his final cock-up inadvertantly saved Her Majesty and he was the hero of the hour again. It contained two sight-gags that made me laugh – one when Hubble attempted to eat a lobster with a knife and fork and another when a room-service trolley concealing him began inching out of the room propelled by his fingers – but another attempt at critical charity failed. I wrote in my notes that I thought the faults lay more in the direction than the script, since if it was played a little more deadpan some of the comedy would work much better. But then the credits revealed that the writers had also produced and directed it, so I'm afraid they're just going to have to carry the can.

Watching The Borrowers – an updated version of Mary Norton's classic – I was suddenly struck by an unwelcome parallel with Anne Frank's diary, in that bothbooks feature a family living in hiding behind the walls, terrified that they'll be spotted by the sinister forces outside. In this version, following that thought, Victoria Wood played a member of the Gestapo and Stephen Fry a sort of Dr Mengele figure, determined to trap the Borrowers so he could conduct scientific experiments on them. I didn't entirely buy Victoria Wood as a Nazi, and neither did those who made the film apparently, since she switched (without clear explanation) from hysterical malice at the beginning to cuddly granny by the end.

The miniature work was great, Charlie Hiscock was good as the little boy, James, and Ben Vanstone had some fun with the Christmas setting (the Borrowers hide out at one point in a nativity scene). But the decision to include a bit of sex interest for Arrietty – in the shape of a cocky biker played by Robert Sheehan – struck me as a slightly tiresome bow to teen manners. Let them watch Misfits, if they want that, and leave the Borrowers alone.