Café Diana is a Princess Diana-themed greasy spoon in Notting Hill Gate. It is a mad place, but it is still the sanest part of Notting Hill because it has the integrity to state its madness bluntly. There is a huge photograph of Diana smiling in the window because she was happy to collaborate in myth-making of any kind. She delivered this photograph herself, and this café returns her love. Its website, which is formal, like a fragment of the Almanach de Gotha that flew away, remembers that she was Baroness of Renfrew when most people never knew it or forgot.

Café Diana is more thrilled by the object of its devotion than the average themed restaurant. I cannot, for example, imagine the Rainforest Café being as excited about any rainforest as Café Diana is about Diana. There are hundreds of photographs of Diana on the walls, in every composition, with every expression: Diana with children; Diana winning a race at sports day; Diana with chains of jewels. It is disorientating, partly because there is also a random photograph of Dustin Hoffman. I feel I am eating inside a colour magazine supplement that re-publishes the same content eternally; or with a very committed stalker. But it is more heartfelt, and so more pleasing, than the official café at Kensington Palace which serves typical English middle-class fare for outings to a palace: necrosis and afternoon tea.

Of course, Diana ate here. Is that fantastical or predictable — or both? She obviously found this dedication to her myth so delightful as to be edible, and she came here many times after it opened in 1988. The report of her initial visit is on the wall as well, in the form of a splash in the People. The accompanying photograph has Diana sitting in the window — she looks like a Diana impersonator — under yet more photographs of herself.

The owner Abdul Basit’s reaction to this visit is also on the wall in a newspaper feature. ‘I was stunned,’ he said then. ‘I tried to stay calm as I brought a cappuccino over to her. My hand was shaking.’

He was going to call Café Diana ‘Café Abdul’, he said, but it sounded wrong, and then he learnt he was Diana’s neighbour. The Russian embassy is also his neighbour, but it didn’t make the shortlist, even if I would have eaten there. Today Basit says from his chair: ‘She liked the full English breakfast.’

There are letters on the wall too. In 1992 her private secretary, Patrick Jephson, wrote: ‘The princess hopes that her familiar “neighbour” and its customers will enjoy many years of prosperity.’ In 1994 he was more ambiguous: ‘The Princess of Wales has asked me to say how touched she was by your birthday greetings together with the beautiful flowers. Though they mark the inexorable passage of another year they are no less appreciated.’ Did she know her office posted existential letters to cafés? In 1997 she wrote in her own hand, plaintively: ‘I wanted to write personally, to thank you so very much for the beautiful flowers you sent for my birthday.’

I eat a bad full English breakfast. They do Middle Eastern food, but it is only 10 a.m.; perhaps that is better? Because the eggs are lukewarm, the sausages are cheap and spongy and the bacon glistens and wobbles horribly. It doesn’t matter. This is not a café at all. It is a specialist archive with only one subject: the co-dependency that sprang up between a princess and a greasy spoon. Royalty makes the human divine and if Café Diana fails to make the same contortion with the breakfast I forgive it for the zeal of the attempt.