One May we rented a house on the shore of Lough Swilly in Rathmullen, Co. Donegal, within sight of the cove that launched the famous Flight of the Earls.

Just after dawn one morning, as my wife and granddaughter slept, I grabbed my camera and car keys and slipped into sweat pants and a plaid shirt and went out the door into the fresh Irish morning. I drove north up the coast road for four or five miles then turned off onto a narrow lane that disappeared between bight…