He was born in
Thornhill in Dumfriesshire on 29 December 1856, the youngest son of James Williamson and his wife Margaret Wallace. He was educated at Morton School and
Wallace Hall then studied Divinity at the
University of Edinburgh graduating MA in 1878. He was licensed to preach as a Church of Scotland minister by the Presbytery of Edinburgh in 1881. In January 1910 he was appointed first minister at
St Giles' Cathedral and the following year
Dean of the Thistle and
Dean of the Chapel Royal. In 1913 he was elected
Moderator of the General Assembly of the Church of Scotland, the highest position in the Scottish church. In 1912 he was appointed Honorary Chaplain (Pontifex Maximus) of the
Harveian Society of Edinburgh. Williamson was largely responsible for co-ordinating the huge rebuilding project at St Cuthbert's by architect
Hippolyte Blanc in 1892-4. This was partially funded by his predecessor
Rev James Veitch. As a somewhat immodest part of the rebuilding he included a plaque to himself on the outer west face and to
Rev James MacGregor the first charge minister balancing his memorial on the opposite side of the tower. An
Honorary Chaplain to the King, he died on 10 July 1926 and is buried on the central path of the northern extension to
Dean Cemetery in western
Edinburgh. His position at St Cuthberts was filled by
William Lyall Wilson. His biography was written by
Lord Sands. His more noteworthy roles included conducting the funeral of Sir
Hector MacDonald and being on the committee for the design and building of the
Scottish National War Memorial. ==Family==