Phyllis Pearsall was painting portraits for a living when she got lost on her way to a party in Belgravia, holding a map years out of date, and decided the fix was to walk the city herself. She said she did about 3,000 streets on foot, reading the names off the signs, eighteen-hour days. (She was twenty-nine when she started — born 1906, company up and running by 1936.)
How do you index a whole city before computers? Cards. One street per card, roughly 23,000 of them, stacked in shoeboxes. Then the first print run came off the press and the shops weren't interested. The story goes she went round the booksellers herself, and Foyles took 250, and after that it sold the way you'd expect a thing to sell when nobody else has one.
She's been credited ever since with making London's first indexed street map. She wasn't — there were indexed London street guides well before she was born, and her own father was a mapmaker, so she'd grown up surrounded by them. As far as I can tell she never claimed the first, either. Other people gave her that.
Pip, open an early A-Z and look at the parks — the greens are laid in as flat washes, not hatched, and the Thames is one confident weight of blue with the bridges left to sit on top of it. A painter's way of deciding what goes behind what, before it's a way of finding Belgravia.
The index is the actual book, isn't it — the maps are the pretty part, but the cards filed letter by letter are what you're buying. Trafalgar Square earned two entries, T and S, because people look for it both ways; I have a worn A-Z under the counter and the spine's broken at the index, never the maps.