THE biggest mound of turkey I consumed over the Christmas and New Year season wasn't on a plate – it was on the box in the form of David Jason's new "comedy", The Royal Bodyguard.

It was almost as unforgivable as the intro you've just read, but at least I didn't use your licence fee to write it.

As the speech marks intone, I use the word comedy in its loosest form. The single funny thing about The Royal Bodyguard was David Jason actually having a bit of a pop at Christmas telly as part of the promotional machine for his show.

His point, and he does have one, is that there isn't as much family comedy on telly at Christmas these days – it's all period drama, soap rubbish and Doctor Who.

But if he thinks The Royal Bodyguard treads anywhere close to being comedy then poor old Del Boy's been lying on the sunbed for too long (or some other poorly thought-out Fools and Horses gag, if you can do better).

I was broadcasting this immense opinion the other day when a friend suddenly and quite dramatically leapt to David Jason's defence, declaring that the actor is beyond reproach thanks to arguably his best-known outing in Only Fools and Horses.

Yes, yes, I like that programme too. But it doesn't mean Jase can star in any old dross and get away without a pasting – and The Royal Bodyguard deserves a ruddy good pasting. And if he's such a national treasure, should we really be celebrating the fact that he has dropped to such an abysmal level?

It's like Mr Bean, stripped of all its charm and humour. Each week, a painfully unfunny and exasperatingly unoriginal scenario pits the bumbling bodyguard against hitmen, thieves, kidnappers and everything else a 10-year-old's imagination could come up with in two minutes.

The writing is woeful and the visual gags so contrived that you'll spend most of the episode listing where you've seen them before.

It just so happens that, as well as hosting the worst piece of festive telly, the BBC also had the outright best in the new Sherlock.

That programme oozed with confidence (quite understandably so after the success of the first series), had the production values of a movie, was brilliantly acted, even more brilliantly directed, and was gripping from the first frame to the last. And... it was funny.

Compare that to the cringeworthily bad gag-a-thon in The Royal Bodyguard and you can see straight away what good writing can do for a programme.

The fact that you can have such a gulf in quality on the same channel is astounding.

More confoundingly, though, is the fact that Sherlock is only on for three episodes while that other bilge is on for six. Work that one out, Holmes.