The Lord High Commissioner to the General Assembly of the Church of Scotland is the British Sovereign's personal representative to the General Assembly of the Church of Scotland (the Kirk), reflecting the Church's role as the national church of Scotland, and the Sovereign's role as protector and member of that Church.
Lord High Commissioners were appointed to the Parliament of the Kingdom of Scotland between 1603 and 1707 as the Sovereign's personal representative. The Act of Union 1707 made this function redundant, but a Lord High Commissioner to the General Assembly of the Church of Scotland has been appointed each year, as the Sovereign's personal representative, since 1690.
Prior to 1929 the General Assembly was held in the former Tolbooth Highland St John's Church on Edinburgh's Royal Mile (this building is no longer used as a church, instead being converted into "The Hub" for the Edinburgh International Festival society). A Throne was provided for the use of the Lord High Commissioner. The union of the Church of Scotland and the (non-established) United Free Church of Scotland took place in 1929. Since 1930 the General Assembly has always met in the former United Free Church Assembly hall on The Mound, Edinburgh. The Lord High Commissioner sits on the Throne in the Royal Gallery, which is technically "outside" the Assembly Hall - symbolising the independence of the Church in matters spiritual from state interference. The very first Assembly of the newly united church in 1929 was held in halls in Annandale Street, Edinburgh (now a bus garage), the only building large enough. Difficulty in accessing the Royal Gallery in this temporary location led to a seemingly trivial but nevertheless embarrassing dispute over protocol, whereby the Lord High Commissioner (the Duke of York, later King George VI) would have had to enter through the Assembly Hall itself - an act of symbolic state interference in the hard-won spiritual independence of the church. The Moderator, Dr John White, was adamant that this would be unacceptable, even suggesting that the post of Lord High Commissioner could be dispensed with. Eventually a suitable arrangement was agreed upon and the office of Lord High Commissioner has survived.