I've been a fan of Herb Lester Associates for a super long time, and have some of their London guides/maps. Their literary guides are a dream: www.herblester.com/collections/...
I think I'm going to get Lamb's London, as I'm making my way through the Slough House books (huge fan).
Authors, cities, characters. Explore the places behind the books – a collection of literary-inspired guides and maps.