Charity shopping is viewed with disdain by the elite of society, they are happy to pay extortionate amounts of money for someone's old clothes, but only on the proviso that you tag the word vintage on before it. My friends and I managed quite well out of ebay etc when we were in university in a town with about three generic shops and we didn't want to wear the same as everyone else. But I digress, I didn't come here to talk about buying clothes in charity shops today.
I've often heard that the best charity shops to browse are those in affluent areas, so Kensington is probably a good bet if you're looking for clothes. I was looking for books however, and this is a reasonably well off area surrounded by universities. I picked up not one, not two, but TEN books I had been meaning to read but hadn't gotten around to for a grand total of £6. I am so pleased. Made my walk to the bank and post office in the rain worth it.