YOU know a TV show has become a success when newspaper columnists start writing about one of the leading men as an Unlikely Sex Object. The surprise is that the object of their affection is Mr Bates. You know, the lame valet in Julian Fellowes’ glorious Sunday night costume drama Downton Abbey.

Bloggers have really taken a shine to Mr Bates who, with all due respect to Brendan Coyle who plays him, is hardly Brad Pitt. Or Colin Firth or Richard Armitage, whose wet shirt (the former) and glowering look (the latter) made the ladies, and some gentlemen of that persuasion, go weak at the knees.

But there we have it in the pages of the London Standard – it’s official, Bates is Downton’s pin-up boy. Bloggers and Tweeters are apparently going mad for the man with the gammy leg.

Some of us find the uncharitable duo of scheming gay butler and snarling lady’s maid far more interesting. How nasty are they? But that’s one of the reasons Downton Abbey has proved the hit of the year in TV terms. Good ratings (despite the BBC throwing the David Terrant/Suranne Jones drama Single Father up against it), good acting, good setting and Maggie Smith stealing every scene thanks to Fellowes’ witty dialogue. Her question: “What is a weekend?” will emerge as one of the year’s best lines.

ITV executives must be patting themselves on the back for taking the gamble and doing the expensive Sunday costume drama that was usually done by the BBC. They must be glad they signed the cheque and have been rewarded with TV gold as viewers got in the Abbey habit.

Of course, at heart Downton Abbey boils down to soap, although with posher frocks, bigger houses and better furniture. But Fellowes has done a marvellous job at planting the seeds for future developments when the series returns, as it will next year with a second bunch of episodes commissioned by ITV.

He’s also kept us on the hop. Just when you think you’ve sussed what’s going to happen, he pulls the rug – Persian probably – from under your feet. Like the randy Egyptian from the embassy who inconveniently died in Lady Mary’s bed and, like some Agatha Christie whodunit, the corpse had to be carried back to his own bedroom by her ladyship and her daughter. This weekend a pregnancy takes everyone by surprise and puts a whole new slant on proceedings.

No one but Fellowes could have got away with all that talk about entails in the opening episode.

Who knew the intricacies of wills could prove so interesting on a Sunday night?

Of course, the success of Downton Abbey might be expected to spawn all manner of rip-offs. One success inevitably breeds another. The BBC is already there. While Downton was filming, they announced that Upstairs Downstairs, originally on ITV, was returning.

The new scripts are by Heidi Thomas, but its creators Jean Marsh and Eileen Atkins have been found roles in this successor which picks up in the 1936, six years after the original – which ran in the early Seventies – left off. Marsh’s housemaid, Rose, has been promoted to housekeeper for the new family at 165 Eaton Place, in London. Dame Eileen fills what we might call the Dame Maggie role as a dowager something or other in the upstairs contingent.

The new cast of Upstairs Downstairs also includes Keeley Hawes, Ed Stoppard, Anne Reid and Art Malik.

Two hour-long episodes are being made by BBC Wales for screening about Christmas time. If it’s successful, and the BBC is looking for a rival for Downton Abbey, then a series is bound to follow.