Born in Scotland, Webster was educated at Cambridge before he came to London where he was called to the bar at the Inner Temple. From 1885-88 Webster was a member of the Metropolitan Board of Works, representing the Vestry of St George Hanover Square. At the 1886 general election he became member of parliament for St Pancras East, holding the seat until 1899. During the First World War, in spite of his age, he held aa commission as a captain in the Royal Field Artillery. He died suddenly at his home in Eccleston Square aged 79, and was buried at Kensal Green Cemetery.