
Naturally I went first to the maps of Sydenham - you see more detail with a magnifying glass. This is from 1825, just six years after the opening of the Croydon Canal, with its large reservoir where Whittel l Gardens and Sydenham Park Road are now

Membership of the London Topographical Society is just £20 a year, for which you get newsletters, a copy of its annual publications, and in non COVID years, an invite to its AGM, always held at some interesting but generally not open to the public venue. The productions standards of the books is very high, and even if you don't like to lose yourself for a hour or so looking at how London was then, you still have about the most stylish coffee table books you could wish for.
Here's where to join
https://londontopsoc.org/