The Common
Cannon Hill Common consists of 21 hectares (52 acres) of land that was once part of extensive holdings belonging to Merton Priory, and was farmed for centuries. Thomas Becket was educated in the priory in 1130, and Nicholas Breakspeare was a monk at the priory in 1125 ,who later became Adrian IV, the first English Pope, in 1154.
The estate was first sold off in 1613, and the land was occupied by Parlementarian forces during the English Civil War. (A row of cottages named "Cromwell Villas" once existed on Cannon Hill Lane.)
Cannon Hill House was built some time in the 1770s by William Taylor, a Major General in the 14th Regiment.
The house changed hands several times until being purchased by Richard Thornton, a Baltic trader, in 1832, who lived in the house until his death in 1865. The house was barely used over the following years, falling more and more into neglect until finally being abandoned in 1880.
Maps produced into the 1930s still show the house, although it was most likely already demolished by 1900.
The land was eventually purchased by George Blay, a local developer (who built most of the houses in the estate(s) surrounding the park), who offered 60 acres of land to Merton Council, who eventually purchased 53.5 acres for £17,610. The park was officially opened in 1927, and the site of the old mansion itself was fenced off and declared a bird sanctuary in 1929
The common was desegnated a Local Nature Reserve in 1998, and today boasts 2 meadows, and mature woodland with some trees as old as 200 years.
Friends of Cannon Hill Common website
Cannon Hill Common on Wikipedia
The Cache
Please do not enter the fenced off area nearby (Protected bird sanctuary)
You are looking for two vines growing along the ground crossing over each other. X marks the spot.
Please do not post spoilers. Thanks 
Logs containing spoilers and/or spoiler photos will be deleted.