Taking the minor road north off the B4507 you pass through the village of Kingston Lisle and shortly come to a cemetery. Park here.
Opposite the cemetery is Greenfield House (the one with the barking dog).
Walk past the house (north) and you can then easily enough make your way through the bushes into the field. I managed this while carrying Sophie with little problem
I walked around the edge of the field keeping the tall garden hedge to my right.
When the hedge finishes you come to a small wooded area which is 'protected' by a barbed wire fence. From this point the Barrow is easily seen amid the trees – totally covered with bushes / brambles etc.
Had I not had Sophie with me I would have hopped over the fence for a closer look but as it was I settled for a view from the field.
On our way back to the car we started a pheasant which flew out of a bush and made myself and Sophie jump. A minute or two later I heard shotgun blasts in the distance. I hope the two events weren't related!
Just visited yesterday. It is located at the extreme north end of the village (opposite the modern cemetary), in a break of trees, marked on the Explorer 170 map as 'TUMULUS' (in capitals - which Rhiannon advises me - means it's Roman)
... and it's in someones back garden with an unfriendly dog.