A line of people sits in the B1 shelter at Wynyard, as two pigeons fossick on the road in front of them. Suddenly a seagull lands on the gutter; it’s the cleanest, whitest, brightest, sharpest-looking seagull I’ve ever seen. It stands there, clear-eyed, upright, regal, a seagull of substance, surveying the humans like an officer inspecting the troops.

But the mood changes. Something intangible shifts in the power balance, and the seagull steps down awkwardly to join the pigeons on the road. It’s as if one of them has whispered: “Not now! You’re not on yet!” And realising its mistake, the seagull is mortified.