You are looking for a small camouflaged round lock-n-lock container.
This area of the estate is known as Otterspool and its heritage stretches back hundreds of years to when it was very popular amongst the gentry who came to relax in the pleasant surroundings including bathing in pools and drinking the water from the nearby fresh water springs. In the mid-18th Century Otterspool House was built and use as an Inn to accommodate those that visited the area. The building survived intact for many years and during the 20th Century when the Wall Hall Estate was in use for education purposes, Otterspool House was utilised as a training hospital. More recently the House has been divided up in a number of flats and cottages. Despite the name and one or two obscure historical sightings, there seems to be no evidence that otters frequented this area at any time.
... to get to the next cache in the series, with the golf course on your left, follow the footpath towards Berrygrove woods, reciting your best joke aloud for any golfers or squirrels to hear.