"and jumped him over Hampstead Heath"
(locally known as "the Heath") is a large ancient parkland in London, covering 320 hectares (790 acres). The parkland is public and is one of the highest points in London, running from Hampstead to Highgate.
The Heath is hilly, and includes ponds, recent and ancient woodlands, a lido, playgrounds, and a training track, and it adjoins the stately home of Kenwood House and its grounds. The Heath has long been a popular place for Londoners to walk and take the air.