Ian was born in Paisley, Scotland on 13 September 1925, the son of a tailor. He attended the John Neilson Institution in Paisley before going on to the University of Glasgow to study Law, after having served in the British army
It was at University where Hamilton became politically active. A participant in debates at the Glasgow University Union, he was a member of the Glasgow University Scottish Nationalist Association and the Scottish Covenant Association. He was also the campaign manager for the successful bid to have John MacCormick elected Rector of the University.
On Christmas Eve 1950, Hamilton, along with three other student Scottish nationalists, removed the Stone of Scone from its place under the Coronation Chair in Westminster Abbey, London. The Stone, originally used for the
coronation of Scottish monarchs, had been removed to England by Edward I in 1296 to bolster his claim to the throne of Scotland. After the Acts of Union 1707 between Scotland and England, it was used for the coronation of British monarchs. As such, Hamilton’s action in returning the Stone to Scotland was applauded as a symbolic triumph for Scottish nationalism. The Stone was turned over to the Church of Scotland, which surrendered it to English authorities in April 1951. Hamilton and his accomplices were charged, but never prosecuted. The Stone was eventually returned to Scotland in 1996, with provision for subsequent use in the coronation of British monarchs.
In 2008, Charles Martin Smith wrote and directed a feature film entitled Stone Of Destiny, based on these events, in which Hamilton was portrayed by Charlie Cox. Hamilton himself had a small part as an English businessman.