William Rose is ok, I wouldnt queue for more than 20 mins to shop there. The butchers in Wood Vale is as good, possibly better, I bought some great lamb there, ditto for the butchers just off Brockley Rise. Both are really friendly and very helpful. I think the good people of East Dulwich have just got a bit excited at having a "traditional" butcher. In saying that it gets a bit of criticism on the East Dulwich Forum for being a bit sniffy.
Personally I miss the butchers from my home town where the meat was locally sourced and had photos of the bovine stock on the wall!