'The Croft' is a park and playing fields in the middle of a residential area between Eastcote and Pinner.
There are two entrances to The Croft - on the southern side you can enter via Cannonbury Avenue and on the northern side you can enter via Glover Road.
The Cannonbury Avenue entrance gets locked at night (9:30pm weekends/10:30pm weekdays), but I think the Glover Road entrance is open 24hrs.