The widespread use of mines in the Great War created an urgent need for vessels to deal with them and paddle steamers were deemed ideal for the job. With their shallow draught and precision manoeuvrability, they proved eminently suitable and large numbers were put into service as the War progressed.
H.M.S. Hexham was one of the eight improved 'Ascot' or 'Racecourse' class minesweepers ordered towards the end of the War and she was built by Clyde Ship Building in 1917. Launched on 15 December, she displaced 820 tons and measured 150 feet in length with a 29½ foot beam and a 7 foot draught. Fitted with diagonal compound engines producing 1,500 h.p., she could steam comfortably at 15 knots and had bunker capacity for 156 tons of coal. With a complement of 52 men, she was commissioned early in 1918 and put in sterling service during the remaining year of the War as well as in the aftermath when many enemy minefields needed rapid clearance. Similar in most respects to the original 'Ascots', the final batch - including the Hexham - were distinguished by the fact that their formasts were situated abaft the bridge rather than in front of it which made for a more balanced design and created better visibility.
Once the wartime minefields had all been swept, most of the minesweepers were laid up. Hexham shared the fate of the majority and was broken up after being sold to Hayes of Porthcawl in 1923.