'For conspicuous gallantry and devotion to duty from 21st August, to 7th September, 1918. During the recent advance this NCO performed particularly fine work. At Miraumont on 23/8/18 when his Platoon Commander was wounded he took charge and successfully consolidated his position and reorganised his Platoon. At Fremicourt on 1st September his Platoon suffered very heavy casualties, only eight men remaining. These he took in hand, and with some others who came to reinforce him, executed flanking movements, personally leading one party, and cleared out two machine guns which had been holding up his Company. He has at all times rendered great service by his clever reconnaissances, reports of which have been of the utmost value to Battalion Headquarters. His steady grasp of the ever changing position and his initiative have been a great example to all.'
Source: London Gazette
Date: 13 March 1919

'For conspicuous gallantry and devotion to duty on 8th October 1918 near Crevecouer. During the attack on the 8th October Sergt Sinclair was acting as C.S.M. and moved forward with Company Headquarters. Owing to the darkness the forward waves overlooked a pillbox from which the enemy directed heavy machine gun fire upon our troops as they passed. Sergt Sinclair, showing great initiative and bravery, and notwithstanding the heavy fire, without the slightest hesitation, rushed the pillbox single handed, killed the enemy gunners, captured the gun, and enabled our advance to be continued. By his action he undoubtedly saved the lives of many of his comrades.'
Source: London Gazette
Date: 17 June 1919