'For gallantry and devotion to duty. During the period 25th February 1918 to 17th September 1918, Captain Dempster held the appointment of Regimental Medical Officer to the Battalion. At all times in the actions and Trench fighting in which the Battalion was engaged Captain Dempster was at his post often under heavy shell fire. Through his ability and administrative capacity, the evacuation of the wounded was carried out with the utmost despatch. At one time, in May 1918, the regimental aid post of our Right Battalion was blown up by shell fire causing casualties to the R.M.O. and his whole staff. Captain Dempster immediately took over the duties of the R.M.O. of the Right Battalion and, until relief came carried on those duties as well as his own. As a R.M.O. his untiring efforts, his utter unselfishness and his devotion to duty were an inspiration to Officers and men alike. No praise is too high for the manner in which Captain Dempster served his Battalion.'
Source: London Gazette
Date: 1 January 1919