On Wednesday I walked through the quietening streets of Belgravia just as the street lamps came on. This used to be a stomping ground; I worked in an office on top of Victoria station for seven years, the heaving bulk of my twenties, and am familiar with the stucco houses and iron-gated garden squares that unfold beyond the platforms. The sky was on the turn, it was too warm, really, as this October has been in general. I was chairing an event at the Italian Cultural Institute, and pushed through heavy doors to find high ceilings and a residue of academic dustiness. The people were friendly and formal, and I felt loud and English and bumbling.

I was there to speak with Riccardo Falcinelli about colour on a stage. When I asked him why he spent 11 years researching and writing, and five promoting, a book about the rainbow, he explained it was because his favourite colour was, and always had been, grey, and he wanted to find out why.

There’s a lot of good stories in Chromorama. It’ll make you look at pencils in a new way, and the colour mauve. I know, now, that a 15th-century person seeing a Madonna in a blue gown in a church was akin to seeing something impossible - paint could be mixed ultramarine for a handsome sum, but fabric couldn’t. Afterwards, I slipped out while Riccardo signed books and everyone returned to speaking Italian. Some places in London never still at night, others never feel loud. Belgravia is one of the latter.

Other good things this week:...