Tension at Sissinghurst as Poirot meets River Cottage

Am I going mad? Don't answer that. Merely clarify one thing. Is BBC4's new Sunday night show Sissinghurst a fly-on-the wall docu-series about the various ways in which the National Trust resists the pressure for Vita Sackville West's beloved Kentish castle and gardens to be hauled into River Cottage-ville with their own sustainable veg plot and sheep farm?

Or is it, in fact, a slyly vicious attempt on behalf of the castle's owner, the writer Adam Nicolson, to take revenge on his wife, the professional gardener and food expert Sarah Raven, for crimes committed previously in their marriage?

So far as I could tell, in the opening episode of the series, the seemingly mild and likeable Adam is seen doing innocent things like writing dreamily on his computer and wandering his estate. He looks like a nice man. He is famously a nice man. His laugh is high up and keen and his hair trembles like an entertaining squirrel that just died on his head. He wants things to go well at the new-look Sissinghurst and to only make changes everyone can live with.

Who orders someone to steam a posy of dead wild flowers back to life?

"I feel a real part of what's happening here!" he whoops when he gets the green light from the Trust to dig out some photos of how the park used to look when Vita had her own sheep, and he strolls back to his quarters along hedgerows, looking as happy as a person can be.

But then he is seen in his kitchen clutching cut flowers in a little mug, looking scared. He went out and they died! He'd been firmly told to steam them by his wife before doing anything else! "Her parting words were steam them," he says.

One is immediately puzzled. Are you trying to tell us something, Adam? You must know how odd this is sounding. I mean, what kind of person outside the Brothers Grimm leaves someone behind in a stone kitchen with strict orders not to emerge until the have steamed a posy of dead wild flowers back to life?

Then we meet Sarah. A substantial woman in a Withnail coat and red leather hobbit boots, she strides purposefully across a field she wants immediately turned over to the growing of rustic Italian vegetables for the Sissinghurst restaurant, which she is convinced serves too much protein.

My heart went out to Sarah - I'd like her if she weren’t so fucking awful

The restaurant is fantastically popular, full of grannies who have just dared to leave the house for the first time this spring and are diving into their plates of exploded sausages and imported racks of lamb swimming in Bisto. The food looks delicious. Everyone loves the food – everyone except Sarah, who wants to put little jugs of oil and vinegar out on the tables, like the Italians.

But we're not Italians, says the head chef, reasonably. People in Kent like to know where they are with their salad. "Then we must teach them!" mocks Sarah. Next the chef is seen swallowing hysterically in her company when he realises the honey in the store cupboard is Spanish, and not local.

Next Sarah is seen resolutely looking at her feet when Adam says he loves the general public. Next we see Sarah at a table assiduously at work underlining in coloured ink in a Liberty-expensive parchment notebook her ideas for improvements to the whole site ("A new chef? With Sarah to do the interviews." "Risotto." "A good shed.") My heart went out to her. I'd like her if she weren't so fucking awful.

But then nobody is coming out of the programme well - apart from Adam, who is, I am convinced, a Machiavelli on a mission to allow cameras into