PetersfieldPoodlePosse: With the sign gone we have decided to archive this one. I popped past on the dog walk this evening and retrieved the cache and its contents, the box will soon be recycled in another location I'm sure
For those of you wondering how the puzzle worked, the sign identified a number of different types of pre-historic barrows on the heath with a number to identify the location of each type on the map of the heath also shown on the sign
Barrow types were disc, bowl, saucer & bell - substitute the numbers then do the maths - no algebra required