Jennifer Westwood in ‘Albion’ mentions this folklore (p398) – which in her words ‘smacks of Druidism’ and hence probably Victorian fantasy. But it’s a nice one.
At sunrise on Midsummer Day the ‘Shining One’ was said to walk along the avenue. His coming was heralded by the call of the cuckoo – the bird of Tir Nan Og, the Celtic land of youth.
{In your fieldnotes, didn’t you hear the cuckoo before your visit, TomBo?!}
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And with regard to how Callanish was made –
A priest-king came to the island bringint the stones with him and black men to raise them. He was attended by other priests and all were adorned with bird skins and feathers.