I don't know one in London, but I found online a company that makes bespoke shoes and sells online all over Europe. if you are interested in the site is www.bespokeshoes.it
There are a few shoe makers and they vary in price, more for men than for women, Lobb's are really good, only have a pair of boots and they have lasted me 10 years so far, as they don't have a lot of different designs and even then they were more than 5K, a friend of mine swears by James Taylor, same price range.
Crockett and Jones make lovely shoes. If you are after boots their Audrey style is super nice and very comfy (they are a ladies’ style). My OH loves their men’s shoes too