Actually a Peel Tower.

Peel towers (also spelt pele), are small fortified keeps or tower houses, built along the English and Scottish borders in the Scottish Marches and North of England, intended as watch towers where signal fires could be lit by the garrison to warn of approaching danger.

Ayton Castle sits on the edge of a plateau overlooking the River Derwent and the villages of East and West Ayton. It was built in the late 14th century, probably by Sir Ralph Eure, and was a typical Northern tower house.