It seems that the Giant’s Quoiting Stone may once have been part of a pair of stones, Samuel Lewis writing in 1831 states,
‘In this parish are the small villages of Port Erin and Port-le-Mary. Between these villages are the Giant’s Quoiting stones, two huge masses of unhewn clay-slate, about ten feet high, three feet wide and two feet thick. Within a mile of these is Fairy Hill, a barrow situated in a low morass from which two defiles lead to Port Erin bay and the creek of Fleswick: the hill is a truncated cone forty feet high, and one hundred and fifty yards in circumference, completely surrounded by a deep and wide ditch; on the summit is a circular excavation ten yards in diameter, with a regular parapet; the sides of the hill facing the defiles are almost perpendicular, and on the north-east side a a pathway to the summit is discernable‘
From ‘ A Topographical Dictionary of England’ by Samuel Lewis 1831 vol 3, p230.
The Fairy Hill mentioned seems to be marked on the modern OS map as a ‘Motte’ just to the north east of Port Erin (SC205 696). The other Quoiting Stone is said to have stood on the slope of Cronk Skibbylt behind Cronk Road.