2nd hand classical Lps in London

You basically need to avoid touristy type places that have shops flogging to tourists with tourist prices. Head for the Thrift/charity shops such as Oxfam & Age UK, check on line for the location of these shops.
My local Oxfam store for instance has about 20/30 classical box sets, some are opera's, but not all, and approx 50+ albums, I don't really take much notice of the vinyl section as I only buy cd's. The box sets usually sell from £2.99+ if my memory serves me.

Thanks for the advice. I was hoping to find an actual music store with a decent and organized collection rather than resorting to the charity shops with a few random and moldy LPs sitting in the corner (though I am happy to give them my business for many things!). There doesn't appear to be a London version of Amoeba Records or any similar shop that you see in the biggest US cities. Pretty sad for a city of this size and such a musical richness in all other ways.

Try the Classical Music Exchange in Notting Hill.

Get yourself to the Camden high street- tons of cheap record stores there in the market. More Jazz and pop but enough classical music as well.