As a naked Winston Churchill putters by, big head bobbing on top of the water, mouth puffing in and out on a cigar that isn't there, we do wonder what we've let ourselves in for. There's only one way to get the full Energybase experience though, and by god, that's what we're going to do.
Skinny dipping may typically be the sort of folly reserved for people with access to something resembling a climate, but this is a November afternoon in central London — and people are doing it en masse; most of them, presumably, sober. For two hours each Sunday, this Bloomsbury pool is requisitioned by Naturist London, with Londoners (99% male it'd appear) queuing round the block to whip off their kit and take the plunge. Queuing quite literally, too — by the time we arrive, there's a one-in, one-out policy, the bare bodies lined up along the poolside.
Nudity may not be optional, but swimming is. For every former wartime prime minister doing his lengths, there's someone shirking in the shallow end, chatting with his neighbour — today, we catch snippets of best flirting practice and the secret to baking good drug-laced brownies. Spend the full two hours here and who knows what trivia you'll come away with.
And that's the beauty of the place; Sundays at Energybase aren't aren't so much a swimming session as a social club — somewhere to put the world to rights while cooling off from the evils of last night. That it's all played out in this eccentric tank of water only adds to the fun of it. With its sloped ceilings and uplighting, its powder blue paintwork and its subterranean windowlessness, the pool — used in 1963 for a Beatles photo shoot — becomes a kind of futuristic Roman bath, as imagined by a 1960s sci-fi B movie. It's an uncanny place, for a unique London dip.