Where are all the polishing stones?

Polishing stone on Fyfield Down (from Celia Haddon's site:
http://www.celiahaddon.co.uk/standing%20stones/wiltshire.html)

Pete G has raised an interesting point. If the bluestones and sarsens were transported for great distances overland, there must have been a need for hundreds --- if not thousands -- of rollers or heavy timbers for sledges. That means many thousands of trees felled. That means many thousands of stone axes and other stone implements, which needed sharpening and smoothing. So where are all the polissoirs or sharpening stones? Pete mentioned this one to me:

Quote from Celia: THE POLISHER STONE, FIFIELD DOWN. SU 128 715
Up from Avebury along the Ridgeway towards Barberry castle, just past boundary stones on the side of the track and near the head of a gallop. Said to be a Neolithic stone, used for polishing stone axes, but I don't know how the grooves can be dated exactly. It could have been used to strop shepherd's tools later in history rather than prehistory. Julian Cope says it is estimated to have been used for 1,200 years (see his Modern Antiquarian book).

There is another one in Leafield in Oxfordshire (LEAFIELD SP 316 153). But where are the hundred of others that we might expect in and around Stonehenge and (if the stones were carried by our heroic ancestors from Mynydd Preseli)in eastern Pembrokeshire?

Part of the problem, of course, is to know which grooves and hollows are prehistoric, and which date from recent times, when farm labourers needed to sharpen their scythes and sickles on suitable stones close to the places where they were working....