WHAT is this obsession with Downton, our captivation with chinless wonders, crusty dowagers and rumblings down below?

At a screening in London this week for the new film, when the opening scenes panned across the 17th century 5000-acre Highclere estate with its towering oaks and Capability Brown lawns the audience burst into simultaneous applause.

But why in the name of Lady Mary would that be the case? Had they all been at the sherry for hours beforehand?

Downton Abbey wasn’t even a good television series. Focusing on the lives of the Crawley family and their bootcleaners it featured a clutch of sublimely daft storylines. Who can forget or forgive handsome war hero Matthew Crawley’s transformation from shrapnel-induced paralysis victim to Charleston dance winner in a matter of filmic hours? Clearly his spinal chord was more robust than writer Julian Fellowes’ commitment to believable narrative. As such, we had the horrors of the First World War reduced to a wee sore back followed by a welcome tingle in the trenches.

How about the story where the dependable, boring Earl of Grantham snogged the chambermaid in the sherry cupboard? Or the tale of Tom Branson the IRA chauffeur falling for Lady Sybil? And who can forget the day when Upstairs took on Downstairs in a game of cricket? And when Branson made the catch the apprentice terrorist was welcomed into the Crawley family, his yearning to blow up the Empire now love-bombed away. (Perhaps that’s the answer to the cataclysmic divisions that wreak havoc in modern society – Remainers and Leavers should set up stumps and play cricket, the winner taking control).

Downton wasn’t always bad. We could just about go along with the storyline in which Mrs Hughes somehow managed to remove footman Thomas’s homosexuality, as if it were a stain on his best shirt rubbed away with a bar of green carbolic. But the expositional dialogue has often been excruciating. “I’ve retired from racing cars because I killed someone,” said Henry Talbot.

Clearly, Fellowes could never be accused of making his audience over-think. So what’s the lure of this take on early 20th century upstairs-downstairs life? Actor Jim Carter says it’s like climbing into a warm bath. It’s certainly familiar, but then so is sweat rash.

And Fellowes assumes his viewers aren’t overly keen to learn of the changing structures of society post-General Strike, the transformative impact of a mobilised working class. That’s why he’s set the movie in 1927, and the central plot features the arrival of the King and Queen, which lends itself to lashings of pomp and circumstance, fabulous frocks, fabulous lifestyles and, it’s revealed, more than 100 horses.

Social commentator Rhiannon Lucy Cosslett believes deference is still a factor in modern Britain. “There seems to be a little bit of Downton-ish forelock tugging, a they-were-good-to-us-up-at-the-big house feeling of residual inferiority.”

There is also an argument that Downton offers a fantasy we crave. And it’s easy to understand why we want to escape a world of zero hours contracts, House of Commons Speakers crying and high streets closing. But isn’t it strange we should seek refuge in a 300-room building which owes its existence to tied employment and de facto white slavery?

And if audiences are keen to escape our selfie-obsessed, narcissistic Instagram world why would we take pleasure in watching men being preened and dressed by butlers, and women presenting themselves like wedding cakes?

I know, this isn’t a Ken Loach movie. We can’t expect ITV to overly dwell in the servants’ distempered box rooms with their tragic little broken-framed photographs, or indicate the stench of pervading loneliness, with close ups of the servants’ hands revealing black coal dust, even though that would have been the reality.

But the lack of believability confines Downton to the coal bin of nonsense. It’s a history show that treats historical markers like lily pads to lightly step across in the pursuit of silliness and soapy storylines. It’s two hours and 3 minutes in which the upper classes get to be fragile and patronising but always in control.

That’s why the film doesn’t focus so much on a world ready to invite a Depression and Fascism to its door – but the state of the big house’s boiler.

The Downton reality is that it’s not quite as good as Coronation Street, a series which doesn’t expose the exposition or resort to characters suddenly acting so counter intuitively.

Jim Carter says the film “celebrates England as it never was.” Keep that in mind when you see it on Friday.