I live in east London and I often walk down Bow Creek from Bow Locks to the A13 via Cody Dock. In all these years, I’ve only seen the parliament of crows once.

It was a warm afternoon, and the tide was low, exposing a beach at Bow riverside as the river doubles back towards the A13. There’s a colony of crows here: they dance in the updrafts from the airconditioning of the Amazon and DPD depots.

This time, though, there were more crows than I’d ever seen - all massing at the riverside. More crows came. More and more crows from the City in the west, Stratford in the north, and Essex in the east, looping towards the river, dark streams in the sky. Some crows barrelled under the bridge that carries electric cables across the river, and playfully zig-zagged across the Lea, screen-gliding like waterfowl, wingtips grazing the water before pulling up to land on the beach.

The crows all settled on the beach on the Tower Hamlets side. The arranged themselves in concentric circles, hundreds of birds, maybe a thousand, with more joining outer circles. The caw-ing was deafening. The warm afternoon stood still. The pigeons roosted on the industrial estate. The coots and moorhens hid in the reeds. The parliament reached a crescendo - and then at a certain moment, their decision was made. The crows at the centre lifted off, spiralling west, east and north. (They never fly south beyond the A13). The sky darkened as the parliament dissolved and hundreds of crows took off together, returning to their territories, leaving only the birds who dance over the warehouses picking for morsels in the river mud.