The Cédric Grolet at the Berkeley lives in the shiniest hotel in Knightsbridge, though I prefer the Mandarin Oriental, because it looks like the crown of a toppling king: no matter what they spend on it, it seems in danger of falling into Hyde Park. The Berkeley operates a pass the parcel for restaurants and, for now, Cédric Grolet (the World’s Best Pastry Chef 2017) has it.

The Berkeley has a fondness for mad teas, which is, by itself, a cognitive dissonance, as I haven’t seen a fat person in Knightsbridge since the 1990s: perhaps they are all dead. I have eaten a shoe biscuit here during London Fashion Week because some women like to eat shoes and there is nothing wrong with that.

This is, at least partly, a ludicrous bakery, as well as a fable that tells us that no mandarin is as good as a real mandarin, and the act of trying to make a fake mandarin when a real one is better is something pitiable. It is not perfect for Instagram, which is the obvious remark. It is too perfect for Instagram. It makes Instagram look like the oil-rig graveyard near Hartlepool.

The window on to Knightsbridge is filled with flowers, maybe poppies, maybe silk: Dorothy’s poppies blowing on the A4. There are pictures of pastries doing things they should not: being bicycle wheels, for instance, or sitting on a carpet, which they match. Anything can be a cake is the message here: cake can save you. But it is performative. The floor of the kitchen is stone fish-scales; the fridges are mirrors. On the counter the cakes sit under glass domes like sculptures: a fake mango, a fake apple, a fake fried egg (if it is meant to be a fried egg).

The dining room is saner: that is, it does not look like one of those laboratories in adverts in which chefs dressed as anaesthetists stick hypodermic needles into truffles, just pinker. It is a series of goldish nooks with lamps that look like daffodils. This is, despite the gilding, a themed restaurant, and the theme is paradise lost. It has more in common with the Rainforest Café than it knows.

We have the Goûtea for £85: a seven–course tea with surprise course (a small sponge). We were supposed to have two, but when I saw the size of it I begged off.

There is a cheese croissant, a fish tart, a fake mandarin, a vanilla flower tart, a scone, a cookie – they mean biscuit – and an immense pistachio and praline tower. It was very overwrought in looks, which doesn’t serve it: don’t all illusions turn to dust in the mouth? Aren’t they supposed to? I cut the scone open. Grolet does jam first. But by some alchemy of placement, he also does cream first. This is an authentic political act: does he know that? How does it taste? Not great – I like a patisserie with fat people, I trust it more – but that hardly matters. I doubt the people here will do more than nibble. Even so, I think it needs more sugar, and more cream.

I console myself with the room. There are stone columns; walls of fine wood; a bathroom sink that is a long, undulating piece of pink marble. I have never seen a sink like that. If it is all faintly Barbie’s Dream Palace (the five-year-old, dressed as Violet Elizabeth Bott at the next table, loved it, humping the banquettes as her mother chided and her father stared grimly at his phone) or London’s most expensive reclamation yard stuck together with matchstick glue, it isn’t unpleasant. It’s too flimsy – too credulous, too fragile – to hate, and soon, like Dorothy, it will blow away.