Whilst poring through the maps bit of a 2nd hand bookshop, I found an OS one-inch map for Swindon, revised 1961, and picked it up.
Comparing this with the modern Explorer for Marlborough (which I take the weatherproof version of from the library prior to every visit), I spotted some differences: on the old map, there's a long barrow beside the circle at Winterbourne Bassett. Another circle at East Kennet too. On the other hand, Falkner's circle doesn't appear on the older one.
Can anyone tell me if these places have been destroyed since the sixties, or just not significant enough features of the land to make it the map anymore? Were they reclassified, found not to be what they were originally thought to be?
I'd love to hear from anyone who can shed light on these.