Following the death of the incumbent William Kenyon-Slaney, Stanier was elected as a Unionist Member of Parliament for Newport, Shropshire in a 1908 by-election.
He held the seat until the 1918 general election, when at same time the Newport constituency was abolished and he replaced the retiring Rowland Hunt in Ludlow.
[2] At the start of the war in 1914, he took on the annual post of treasurer of the Royal Salop Infirmary in Shrewsbury when their preferred candidate had been mobilized to serve abroad.
[3] Stanier was the deputy chairman of the North Staffordshire Railway and the Trent and Mersey Canal, a director of the Farmers' Land Purchase Company and Home Grown Sugar.
He was also chair of the British Sugar Beet Growers' Society and a governor of Harper Adams Agricultural College,[2] and until a few years before his death was proprietor of the Shrewsbury Chronicle.