I see them every time I take a walk along the Regents Canal between Islington and Camden Lock. There are signs, you know. Not signs like you’d expect (such as “Cyclists dismount” on wobbly pontoons, which are ignored by every bugger on two wheels). No. Old signs. I had a photo once, but it vanished when I first told people about the Metropolitan Board of Worms.

Yes, yes, everyone tells me I just misread the old, rusty sign. “Board of Works”, they say. I disagree. They haven’t seen the spawning pools.

Every time I take a walk along the canal, a few more of them break the surface as I approach the pools, singing their strange hooning songs to me. Occasionally I consider kicking a pigeon into the canal, just to watch them swarm around the bird before it disappears under the foam. They haven’t taken a swan yet, but it can only be a matter of time. They’re growing fast. And then – I wouldn’t want to live on a canal boat after that.

Occasionally I wonder how hard it’d be to topple the next towpath-hogging cyclist into the canal. Much better than a pigeon, don’t you think?