I like these, Paul. You say they're the only ones 'in the area', but do you know of more elsewhere?
They are <i>fairly</i> common in Ireland, but rarely come in threes. They are mini-bullauns.
See:
http://www.megalithomania.com/show/site/30/121
http://www.megalithomania.com/show/site/480/1345
for a couple of examples.