Presenting an addition to my dubious theory of 2006. I found mention in Gloucestershire Notes and Queries v5 (1894), which is about ‘Place Rimes’, rhymes expressing local prejudice about neighbouring villages :)
Charles Hillier the ancient Corunna [Napoleonic battle of 1809] veteran who died at Uley some years ago, aged upwards of 90, added to the above [rhymes]:-- “Nimpsfield heg pegs,” which the old man explained were “things” which grew in the hedges.
And Nympsfield is literally yards from the tump. Etymology eh, you can argue it until the cows come home and it doesn’t really matter, but it is interesting I think.