On 18 June, 22:33, Fig wrote:

Whitestone Pond (which happens, I believe, to be the highest point in London. A pond! How does that work?)?

Artificial, originally used for watering military horses. Reservoir
and fountain nearby. Hampstead is the site of freshwater springs, and
by the early nineteenth century a number of reservoirs had been built
to control the water supply and convey it to London. The Hampstead
Water Company (founded in 1692) had control of the springs and
reservoir and Hampstead water was provided to the west end of London
via Kentish Town.