E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Fife, in Scotland. Called king because Alexander III. of Scotland was killed there.
As he was riding in the dusk of the evening along the sea-coast of Fife, betwixt Burnt-island and King-horn, he approached too near the brink of the precipicë, and his horse, starting or stumbling, he was thrown over the rock and killed on the spot The people of the country still point out the very spot where it happened, and which is called The Kings Crag.Sir Walter Scott: Tales of a Grandfather, vi.