<i>However I am curious about the church in neighbouring Soulbury which is built on a rise/mound? and there is a stone (not sure if is a standing stone across the road from it</i>
Found the stone across the road today, during a drive around Bucks in the sun.

Bit of an oddity, it lies slap bang in the middle of a side road about 50 yards north of the church, emerging from the tarmac with no markings or warnings of any kind. I've uploaded a picture to the Portal (as Natural Stone or Glacial Erratic in the absence of any evidence to the contrary), under Soulbury. If anyone thinks it's more than that, let me know and I'll upload it here too.