Two children had to be rescued from a ledge at the rear of Carrick Castle in the spring of 1968.
The boys, aged 11 and nine, from Kirkland Square, had become trapped by a rising tide.
The boys were spotted by castle guide Jack McIlwaine who reported large breakers in the sea around the fortress, lashing rain and a strong wind.
Mr McIlwaine said: “I heard some faint cries for help. I looked out the archers’ window and there were two boys hanging on to a piece of rope just outside the window between the tower and the castle wall perched on a steep sloping ledge. “
He suggested that the pair had walked across whilst the tide was low.
A police spokesman indicated that it would only have been a matter of minutes before the rapidly rising tide would have reached them.
Carnmoney man William Gregg, a boatman, at Carrick Harbour, tied himself to a rope and was lowered down the 40 ft castle wall by police.
He tied the boys to the end of the rope and they were winched to safety, escaping injury.
A report in the East Antrim Times suggested that the pair had been trying to find a toy when cut off by the tide.