Dermalogica Overnight Clearing Gel
I ordered some online and it arrived just as I had another spot. What is going on? Anyway, for once I didn't mind as it meant I could road-test this. I can confirm it worked brilliantly. I dabbed a teeny bit on the spot and woke up to find it almost gone.
I hope this lasts me for the rest of my life as I don't get many spots. It wasn't cheap so here is hoping!