William Maynard Sinton, JP (1 February 1860 – 31 December 1942) was High Sheriff of County Armagh, an Ulster Unionist County Councillor for Armagh and industrialist.
Sinton was the eldest son, and heir, of Thomas Sinton of Laurelvale House. His father founded the family linen firm of Thomas Sinton & Co. Ltd. (flax spinners). Maynard Sinton attended school at Kendal, Westmoreland and at Newtown School, Waterford. Sinton's uncle was the linen manufacturer John Sinton owner of the Ravarnette Weaving Company; his cousin, a grandson of the same John Sinton, was the Victoria Cross winner John Alexander Sinton. He continued to manage the firm following his father's death and took up residence at Ballyards Castle, Armagh.
Maynard married, on 16 March 1905, Myra Atkinson, of Park View, Tandragee and 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. The Ballyards cup was presented every year at the Armagh point-to-point races.