Last week I went to the Wetland Centre in Barnes, southwest London, in the hope of seeing a spotted crake that had been paddling about there in a reedbed. The Wetland Centre is an extraordinary place: an extensive area of pools and grazing marsh on the site of some old reservoirs, with the Knightsbridge skyline visible far off. Birds such as redshanks and reed warblers nest there, and many migrant birds flying over London come down.

The spotted crake was one of those, and it had evidently liked what it found. It had already been there for a month, always lurking in about 100 yards’ length of reedbed, and occasionally coming out.

It was a fresh, sunny morning, just the sort of morning when migrants take it into their head to move on, so I thought, “It’ll be just my luck to be a day too late.” However, when I got to the hide opposite to where it had conveniently settled, I was assured by one of the watchers that it had already been out but had been chased back into the reeds by a water rail.

“You must look over the water,” I was told, “at the bit of reeds between the Harrods domes.” These loomed up plainly in the distance. So I looked and looked and, having no luck, eventually decided to go and get warm in the sunshine. On another pool I found a heron also warming itself up, facing the sun with its wings half open. When I went back, sure enough, a cry went up: “It’s been out but it’s gone back again.” That luck of mine.

At last, after about four hours, we suddenly saw a dumpy little brown bird, not much bigger than a thrush, come out and walk along in the shallow water in front of the reeds. That was our crake. Through field glasses, you could see its yellow beak and the pale feathers under its cocked tail. Through a telescope, you could see its brown and bluish plumage with white flecking.

Someone said, “Rare birds aren’t necessarily beautiful,” and we all laughed. All the same, this spotted crake — a bird that breeds mainly in distant European marshes — had the strange cachet of rarity that made it a wonder to us all.