Looks a bit like a Dorset ring barrow. There's one at Oakley Down. http://www.themodernantiquarian.com/post/24194
Thanks Juamjei , it does look similar, a long way from home though.
The one in Tiompan's picture does not appear to have an entrance, so I reckon it is a barrow. As always, until someone takes a spade and a trowel to it we'll never know for sure.
There's a few ring barrow's in Ireland too.
http://www.megalithomania.com/show/image/5692