“Is it a stone circle with a later burial cairn built inside it or is it simply a cairn with a permanent stone kerb?”
Don’t be daft. It’s Fingal’s Cauldron Seat, made by Finn McCool. He sat here while he cooked his tea.
There’s a holed stone in the outer circle – this is where he tied up his dog Bran, to stop him making off with the stew before it was cooked.
(from the Atlas of Magical Britain, by J+C Bord)
In one of the stones of Fion-gal’s cauldron seat – Suidhe choir Fhionn – there is a remarkable perforation, which was probably associated with some old superstition or religious ceremony, now forgotten. The hole is sufficiently large to admit the two fingers, and runs perpendicularly through the side of the column. Tradition relates that to this stone Fion-gal was wont to tie his favourite dog Bran.
From p55 of ‘The Antiquities of Arran’ by John McArthur (1861).