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 King's
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894