Name: The butterfly. Age: Dates back to the 30s, although not recognised as a separate swimming discipline until the 50s. Appearance: In most cases, like someone repeatedly trying to catch a mackerel with their bare hands. We’re not talking about the insect, then. No, we’re talking about the swimming style – a combination of overarm lurch and double dolphin kick. Where can I see this stroke demonstrated? Nowhere. Nowhere at all? As you well know, Britain’s swimming pools are closed to help prevent the transmission of coronavirus. Yes, but I heard they’re going to reopen in England soon. Maybe as soon as 4 July! Even then, there will be no butterfly. Why not? It’s prohibited in guidelines issued by Swim England in anticipation of pools reopening: “Wide strokes such as butterfly should be avoided when the lanes become busy.” What are the other rules? You should turn up wearing your swimming costume under your clothes, and avoid showering until you get home. They may also have to designate separate entrance and exit steps in the pool. You know what? I may not bother swimming just yet. All the chlorine should make swimming pretty safe, as long as physical distancing between swimmers is maintained. How much? It is recommended that each swimmer has 6sq metres of space. Good luck with that. Have you ever been to a pool? It’s true that physical distancing has long been an issue in lane swimming, with slow swimmers clogging up fast lanes, and the idle and out-of-breath crowding both ends. Pools are places of damp, suppressed fury. And the butterfly? Long been frowned upon by regular pool users. The butterfly is considered show-offy, aggressive and galumphing. Its devotees – mostly men – generate a tremendous amount of turbulence to little effect. It’s also an easy way to give a passing swimmer a black eye. Where did it even come from? It originated with the Australian swimmer Sydney Cavill, who was looking for a faster breaststroke technique. He came up with the idea of lifting his arms out of the water for the recovery phase of the stroke. Let his name be for ever cursed. The addition of the dolphin kick came later, but this broke the official rules set down for breaststroke. Contests featuring the butterfly were first held at the Olympics in 1956. Is it possible that Covid-19 could kill the butterfly stroke for ever? I don’t know, but here’s hoping. Do say: “The pool is open! You can all come crawling back!” Don’t say: “How do I stop my face mask from getting wet?”