Sinclair Winton arrived in Sydney from Scotland at the end of 1912. By 1915 he was playing for Balmain in the first grade as a forward. He had a very successful season, scoring in the Gardiner Cup final in their 2-0 win against West Wallsend to become NSW champions. He enlisted prior to the start of the 1916 season. Before arriving in France, Lance Corporal Winton was transferred to the 4th Battalion.
He was killed on 18 April 1917 when a delayed action mine left by the Germans, exploded at the Quartermaster store in Velu, near Bapaume, three days after the Battle of Lagnicourt. Nine men of the 4th Battalion in total were killed in the explosion. They had been operating the Quartermaster store from that location for about 3 weeks before the hidden mine exploded. He was 28 years of age. Tragically, his fellow Balmain forward and Cup winning team mate William Buttel had been killed in action in France 9 days earlier.