This is one of the tallest remaining barrows in the county despite, or because of, it's use as a ROC monitoring post. When the post was constructed in the late 1950's a large trench some 7 metres long and 3 metres deep was gouged out of the top of the monument and it could be that the height of the barrow was slightly increased in the process of building. Whatever, it stands a respectable 3 metres high with a circumference of 20 metres on the edge of a field next to the B1225 – an ancient trackway with several round and long barrows associated with it. It also marks the highest point in the immediate area with the land sloping away westward to a tributary of the river Witham and eastwards towards the River Bain.
Fact fans: The Belmont aerial mast just to the southeast is the tallest structure in Europe.
Very odd site! I wondered at first if I'd found the right place, as the barrow seems to have been built on/into...
Further research showed that there was a Royal Observer Corps monitoring post inserted into the barrow in 1959, which was de-commissioned in 1976.
(Many thanks to Chris Collyer for the info!).