The Royal Arch degree is not native to Scotland, but seems to have been introduced from both Irish and English sources, often Military Lodges, towards the middle of the eighteenth century. The earliest reference to the degree is at Stirling in 1743.
These Military Lodges introduced many other degrees beyond the Craft, and when the regiments moved on, Lodges in the vicinity sometimes continued to work them. This situation continued until the end of the eighteenth century.
However, the early Secret Societies Acts caused the Grand Lodge of Scotland, in 1800, to issue a warning to its Lodges against the working of any degrees other than those of Entered Apprentice, Fellow Craft and Master Mason.
Many Lodges heeded the warning and the additional degrees associated with Royal Arch or Templar masonry had to be worked in assemblies separate from the Lodge. The feeling grew amongst the Brethren that these assemblies should be legitimised in some way. A few obtained Charters from the Grand Encampment of Ireland. Others petitioned the Templar Grand Body in England and in 1810, under the patronage of the Duke of Kent, the Royal Grand Conclave of Scotland was chartered and Alexander Deuchar appointed its first Grand Master.
This Royal Grand Conclave was empowered to grant Charters for the conferring of the Knight Templar grades upon those qualified as Royal Arch Masons. Deuchar soon realised that it was unsatisfactory to have first three degrees and the Knight Templar grades under proper control but not the intermediate, qualifying, degrees of the Royal Arch.
In 1815 he convened a special committee, and all bodies in Scotland known to be working the Royal Arch degrees were contacted, with a view to forming a Grand Body to exercise proper control. All three Home Grand Lodges were consulted, so as not to infringe upon their interests. Advice was sought, in particular, from England where the United Grand Lodge of England had recently been formed, and where the status of the Royal Arch degree had been acknowledged, as the completion of the third degree.
The Earl of Sussex was supportive, and advised Deuchar to make every effort to persuade the Grand Lodge of Scotland to adopt a similar stance, and take the Royal Arch under its wing. However, after an initially encouraging reply from the Grand Secretary of the Grand Lodge of Scotland, the matter became inextricably bogged down in Committee.
Eventually a meeting of interested Chapters could be delayed no longer and, in August 1817, representatives of 34 Chapters met in Edinburgh and the Supreme Grand Royal Arch Chapter of Scotland was erected and consecrated. Charters were issued, and the new Grand Body grew slowly but steadily, and gradually all bodies working the Royal Arch degree in Scotland came under its control.
At its peak, in the 1960's, the Supreme Grand Royal Arch Chapter of Scotland had some 650 active Chapters, many of which subsequently left to form Supreme Grand Royal Arch Chapters of their own, as happened for example in Israel and New South Wales.
There are, currently, some 470 active Chapters, 220 of which are overseas.