I encourage caching by public transport. Take the Northern Line to Archway and continue on Bus 210 towards Brent Cross. Exit at stop Compton Avenue / Kenwood. From there, the cache is within about 200m. A bicycle will bring you very close too.
Hampstead Heath
Hampstead Heath is North London's largest and probably most important green space. The wildest of London's parks has fields to run in, long grass to roll in, woods to hide in and, most famously, ponds to swim in. In north London this is THE place to get back to nature. Strewn with picnickers, cyclists, families and the rest, the heath is large enough and has enough copses, hills and mounds that a quiet spot is never far away.
Cohen's Field & Kenwood House
Cohen's field is located in the north east end of Hampstead Heath, near Highgate Village. There's a good view over central London from here. To the right of the view point is the Kenwood House on its extensive Kenwood Estate, just left behind you is the Kenwood House Kitchen Garden - go and have a look if it's open.
The Cache
Go to the above coordinates. Enjoy the view of London and try to spot some of London's monuments.
There used to be an information panel there, from which you would have to calculcate the final coords.
Since the panel has gone, here are the final coords to go there directly:
N 51° 34.319 W 000° 09.811
This is roughly 100m away and on public ground, no need to enter any gate. You are looking for a small brown plastic box, a bit into the bushes. Look for William A. Robinson and hope that he's free - go in right of him. No pen there, bring your own. Please take care to replace the cache so that it can't easily be seen from outside.
Take note of the letter and number under the lid for the bonus cache.
Original contents: 3 geopins (1 British Columbia, 1 Good Karma and 1 Bad Karma)
Wheelchair Users
Probably difficult. Start location is over flat grass, but the final requires to go over a bumpy path/grass, and into bushes.
Hall of Fame
Congratulations to the first finders!
1. Gold went to... The Bongtwashes! on 16 October 2007
2. Silver for rodz on 16 October 2007
3. Bronze for goldpot on 18 October 2007.