Salisbury plain. Old Sarum: [earthworks, ancient field systems, etc.]
[Southampton] :  Ordnance Survey, 
1933.
"C.R. 8306-500/33".
One of an experimental group of 6 sheets, compiled largely from air photography, contour 5.1. = 5 feet. Only this, and the adjoining sheet to the north (Amesbury) are known to have been published.
Phillips gives date as 1937.