It's definitely got Ogham, but is it prehistoric? I dunno. It's right next to a very old churchy spot, complete with very old ruined church, so it's got that feel of 'Christianised site' a bit like what I imagine Manx Keeils are like. A bit of reading has got me fairly sure this is the Cnoc-a'-Charra, or 'the hill of the pillar.'
It's quite unlike the confirmed prehistoric stone up to the north of the island. This one is much more dressed looking. It's also not in it's original position.
I was slightly miffed that I didn't get time to go looking for the similarly unmappped 14ft fallen stone known as the 'Achadh-a'-Charra', to the west of St. Cathan's, currently on drain-cover duties.
I'd hoped to find the two other stones nearby, apparently known as 'The Cailleach and the Bodach', but they aren't mapped, I had no guide, and it was getting dark. I bottled out.
In retrospect, I wonder if the plethora of names which seem to be applied to stones on Gigha might mask the fact that this stone and that covering the drain nearby, might not in fact be the Cailleach and the Bodach.
From 'Notes On The Standing Stones of Kintyre', by Duncan Colville, 1929.
"North-east of Achadh-a'-Charra, at an equal distance from the Chapel, is Cnoc-a'-Charra, or 'the hill of the pillar.' On the top of this hill there is another stone 9 feet long, and 3 feet 10 inches in circumference; of the 9 feet, 2 feet are in the ground. Still farther to the north-east, on a higher hill, there was a cross which fell some years since, and was broken; the three stones were in a straight line."
This pillar on Cnoc-a'-Charra is now well known on account of the Ogam inscription incised upon it, and a most interesting description of it4 will be found in the first number of Scottish Gaelic Studies, published 1926. There we are told that in the course of last century it twice fell down, and on one of these occasions a length of about 2 feet broke off athe top, and is now lost. Consequently it now stands about 5 feet 9 inches above ground. Detailed particulars of these accidents will be found in Rhys's account of the stone in vol. xxxi. of the Journal of the
Royal Society of Antiquaries of Ireland, from information supplied by the parish minister, the Rev. John Francis Mackenzie. The damage was said to have been caused by some quarrying operations in the hillock, and that it suffered further rough treatment may be gathered from the remarks of another writer, who records that several times the pillar was pushed over by the lads of the neighbourhood, and subsequently replaced by the orders of the proprietor.
It may be of further interest to note that on 27th June 1899 this stone was inspected by a large party of members of the Royal Society of Antiquaries of Ireland, and of the Cambrian Archaeological Association, who visited the island in the course of a specially organised archaeological trip to the west of Scotland in a steamer chartered for the purpose. A description of this visit, illustrated by a photograph of the stone, was published in the Journal of the first-named Society