L E Went are still in business. They are about a mile from me. Ya could also try Metalflake - Welcome To Metalflake in Chessington. I got all my paint from them a couple of months ago. Very extensive range of over 6000 products. Hope this helps, Rog.I have used LE went in new Malden a few times in the past. If there still in business they have lots of classic paint codes.
Or try searching standox paints supply's they are very good at finding codes.