This is a cylinder, big enough for small trackables, about 15 feet up a tree. I don't want it to be hard to find, for geocachers - so use the hint. To make it hard for muggles to see, even once the leaves have gone, please try to wrap the string round so that it's facing into the woods and away from the path.
As with any tree climb, don't attempt it if you're unsure of your abilities. It was three branches up the way I did it, and I was safely lodged in a fork in the branches when fixing it in place. So it's not all that precarious.
The wood is home to a fairly ferocious nettle patch so don't go here in shorts! Looking at the logs, some people have accessed directly from the north but there's a way in from the south too.
Have fun...
NB you should NOT be riding a bike or a horse along here: The Thames Path National Trail is not a long distance route for cyclists. Most of the Thames Path is a public footpath on which cyclists have no legal right to ride unless they have permission from the landowners - cycling without permission is a trespass offence against landowners. However there are some sections of the Thames Path outside London which cyclists can use - the longest section being the 5.4 miles (8.7 km) through Oxford and the 5.8 miles (9.4 Km) from Weybridge to Hampton Court. Cyclists wanting a long-distance ride should not attempt the Thames Path. http://www.nationaltrail.co.uk/thames-path/information