The bloke in Pedal It (18 Newington Causeway, SE1 6DR) was as nice as he was a month ago, gave me a £25 discount, a free back light, and a promise that if I came back tomorrow, I could look through the bucket of discarded mounts and see if I found one that matched my nice front light (which was in my pocket at the time of theft). I mentioned my previous bike (a Decathlon) was a bit heavy, and so he sold me a Ridgeback, which seems to be made of shadow and moonbeams.
He sent me down to Halfords on the Old Kent Road, as he had done the first time for a helmet & reflective gear, only this time it was for a sturdier lock than the one he's previously sold me. It didn't seem such a trek this time, partly because I'm more used to cycling, and partly because hey, light bike. As I went in I heard some guy yell "Hey!", and it was himself again, advising me to get a good lock. It turns out that he was there to pick up his girlfriend, a Halfords employee, who he then plonked on the back of his motorcycle and drove away with. Hrm.