According to his monument in the parish church of Berwick, Fenwick died on 15 March 1657, and this is confirmed by the fact that a new writ for Berwick was moved on 26 March 1657. His will, signed 8 March 1657. In some accounts Fenwick is confused with Lieutenant-colonel Roger Fenwick, who was killed in the Battle of Dunkirk, 4 June 1658.