On the tube with my trusty shoulder-bag – it feels like travelling again. The Miró exhibition is terrific, from his exquisite stylised painting of a farmhouse through to big white canvases with a single black line crawling across them; ladders reaching to the sky, comic cartoon faces, asterisks for stars – much of it thick with his revulsion for Franco’s fascist regime. Tate Modern is bustling with tourists and Londoners – it’s proof of the pull of art.

In the Member’s Room for lunch and a beer, I’m curtly rebuffed each time I ask ‘Is anyone sitting here?’ So, grumpy, I’m out on the roof terrace, looking at the rising phallic Shard topped by its high crane, and the tower of Southwark Cathedral and the roof of The Globe Theatre, until the rain starts to spatter my sketchbook. Inside the galleries: there’s one room with a sheer red mesh ceiling and, hanging from it, a red fabric staircase, a full-size staircase, rippling as people walk under it; they laugh, or stand open-mouthed in awe, or take pictures. It’s amazing, but some just walk through, bored…

Tiny Giacometti figures sprout from a heavy block on long legs, four women in a Paris brothel: ‘The distance seemed insurmountable in spite of my desire,’ he wrote. I draw a striking woman watching a video, then go into the dim Mark Rothko room – the big dark red abstracts vibrate, mysterious as Stonehenge, and still give me goose-pimples. There’s always a hush in there – it is, for me, the most powerful room in the building, a secular chapel.

I watch a long video of garbage blowing around in the street: “American Beauty – c’est la même chose’ says the man next to me. Maybe, but it’s totally mesmerising: a burger box chases paper round in a circle, snapping at it; a plastic spoon tries to heave itself over, a broken umbrella skitters nervously along the white line. You can’t help laughing at these silly dumb creatures in their street ballet… Is this a waste of public money? Not to me.

In the shop, I misread a book-title: ‘How To Paint Ike Turner’…