There I was: sitting in the pub, minding my own business, when my leg started to burn. I hadn’t dropped a cigarette on it (smoking ban, remember?), nobody was using a magnifying glass to focus the sun’s rays on it, and it was safely esconced in a pair of jeans. Nevertheless, my leg was burning.

Off to the bogs I trotted, and sure enough, my leg *was* burning. A bit of skin on my thigh, roughly the size of a 50p piece, was showing all the signs of a pretty nasty sunburn – but it hadn’t been in the sun. It was, however, right next to my pocket. The pocket where I keep my burny things!

Actually, I don’t keep burny things in my pocket – just keys. So it had to be something on my keyring – either the little LED torch, or the glow in the dark tag I bought from The Register a few years ago (it’s radioactive, but El Reg promised that it’s perfectly safe – like the glow in the dark dials on a watch). Neither of them seemed to be hot, but when I took them off the keyring and got rid of them, the burning stopped.

I’ve still got the burn (and it definitely *is* a burn, not a scratch, not an insect bite, not chafing from an errant car key), but I’m none the wiser about the cause. Maybe it was acid leaking from the battery in the LED torch, or – more worryingly – maybe there is a hairline crack in the luminous tag, and it somehow managed to give me a radiation burn. It’s all very mysterious.