his death in 1790, Roy held the position of Colonel of the 30th (Cambridgeshire) Regiment of Foot. Active service On the termination of the Scottish survey Roy, now under the jurisdiction of two military bodies, was posted in 1756 to the South of England where he was engaged, together with Watson and Dundas, in inspecting the readiness of coastal military installations in preparation for an expected French invasion. This work involved Roy in the production of plans of fortifications and rough maps of stretches of the south coast: examples are a sketch of the country from Gloucester to Pembroke, with Milford Haven and a sketch of the country betwixt Guildford and Canterbury. These sketches are preserved in the British Library. By 1757 Roy was with his regiment in France for the Rochefort expedition and then in Germany for the Battle of Minden in 1759. His technical abilities and willingness to innovate brought him to the favourable attention of his commanders. Preparatory to the battle, the various military engineers made drawings of each step of the coming battle, with each step drawn on a different sheet of paper. The commander could then study the course of the battle before it occurred, going from one sheet to the next. Lieutenant Roy, however, made his drawings on a single sheet with coordinated and accurate overlays, so that the commander could more easily study the course of the battle by examining a single sheet of paper. The commander's comprehension was greatly facilitated, and Roy's methodology was soon adopted as an advancement in military science. Thereafter his promotion was rapid, and by the end of the war in 1763 Roy was a lieutenant colonel in the regiment and director of the engineers of the Board of Ordnance as well as being the deputy quartermaster general for Germany. Surveyor-general At the conclusion of the war in 1763 Roy returned to London, where he was based for the rest of his life. The threatened French invasion of the south coast had never materialised, but he felt strongly that the reconnaissances he had made with Watson at the outbreak of the war should be extended to a national survey, not just of the vulnerable south but the whole of the British Isles. He never ceased to champion this cause, but the expense of the Seven Years' War and then the American War of Independence excluded any expenditure on