Had a quick look for this after visiting Windmill Tump, as it is very close by. If the intervening trees and walls were removed, the older long barrow would probably be visible from here.
The barrow is in a narrow band of trees on the north side of a minor road from Rodmarton to Cherington. It's difficult to work out where exactly the barrow is, even in the low winter vegetation. There is a large amount of limestone scattered about in the bushes, as well as various badger holes and root damage. There has been a dry stone wall running on the north side of the trees, most of which has collapsed, adding to the general confusion. The 18th century description made this sound like a pair of decent barrows, one with a large cist. There's nothing obvious here that would fit that decription and it's difficult to make out what is still extant.
From "Gloucestershire Barrows" by H. O'Neil and L. Grinsell (1960):
" 'Mr Lysons exhibited an urn taken out of a tumulus ... in a field called Inlands ... in the year 1779. It was deposited in the centre of the tumulus, in a pentagonal cell about 2 ft. 5 ins. deep, formed by 5 large hewn stones, over which was placed another very large stone to secure it. ... In the urn was a considerable quantity of ashes and burnt bones.' The mound consisted of 'fine black earth mixed with wood ashes, except a stratum of rubbish 20ins in depth from the top.' Archa, ix, 1789, 367.
'Another small tumulus adjoining to the one above-mentioned was also opened at the same time, in which the urn was not deposited in a cell, but was buried in the earth, so that it could not be taken out entire. ... It appears to have been of the same kind as the preceding.' "
The barrow was visited by Leslie Grinsell on 1 November 1959, reporting that it was damaged by badgers. The proportions were recorded as diameter 28 feet, height 5 feet.