Military engineer, surveyor, antiquary. Born South Lanarkshire. Founder of the Ordnance Survey.
1749-55, one of a team that produced "The Duke of Cumberland's Map", commissioned by George II as an aid to subjugating the Scots. Showing Roy's interest in history the map plots many Roman remains. He was promoted up to to major-general, always involved in land surveying, and became a member of the Royal Society.
1784, to assess the relative positions of the French Royal Observatory (Paris) and the British Royal Observatory (Greenwich) he measured a base-line from King's Arbour (Heathrow) to Hampton Poor House. This was the basis for all subsequent surveys of Britain, using the triangulation technique.
Never married. No pictures seems to exist but we found some of his hand-writing.