You are referring to Woodstock in Oxfordshire and Oakham in Rutland.
See image here: http://www.visitwoodstock.co.uk/interest/local/stocks
The purpose of five holes seems to be a mystery, usually they are in pairs (2, 4, 6) for bipedal persons. I cannot locate any historical reason or even hypothesis for it.
discover-rutland.co.uk/xsdbimgs/PDF's/OakhamHeritageTrail.pdf no longer exists