He continued to manage the firm following his father's death and took up residence at Ballyards Castle, Armagh.
The couple had two children, Before the Second World War the family employed over 20 staff on the estate including two chauffeurs, a governess (a Miss Glenda Rowe), cooks, servants and gardeners.
They kept racehorses and a pack of beagles, as Mr. Sinton was a leading light at 'big shoots' and Irish gun dog trials.
Upon his death, without a male heir, his main business interests passed to his brother, Frederick Buckby Sinton, of Banford House, Tullylish.
The Sintons retained the Ballyards estate until the late 1950s and, in the early 1960s, the castle became the home, for a few years, of Vernon College, a boarding school for boys formerly situate at Dunmurry.