Dave Field, an archaeologist who works at English Heritage, has sent me a photo of a fascinating map of the Amesbury estate (I’ve copied a detail above) which adds to the Stonehenge milestone story. He says the map is undated, but he guesses was drawn around 1800.
As he points out, it shows milestone 79 on the Amesbury road, and two milestones 81 after the fork – but only one milestone 80 (those familiar with the world heritage site landscape will recognise the shape of the iron age hillfort, Caesar’s Camp, in the tree plantation with “3” in the centre at bottom right). This confirms that the milestones were moved slightly westwards after 1800 (I’d suggested 1810–1840). But were there ever two milestone 80s, or did they think they could get away with only one by putting it at the road junction? How many of these stones are still out there? And where are they…?