Hugh graduated M.B., Ch.B. at the University of Glasgow on 23rd July 1901. He was a member of the Glasgow Bibliography & Archaeological Society, and author of 'Medical Institutes of Old Glasgow' - Glasgow Medical Journal 1910, and 'Medical Life in Old Glasgow' - Ib 1912. Whilst he held a practice in Glasgow, Hugh enlisted into the R.A.M.C., Territorial Force in December 1914, and was attached as Medical Officer to the 8th Scottish Rifles (T), being stationed at Cambusbarron, Stirling in 1915. He was later transferred to the Royal Field Artillery. Hugh gained the rank of Captain on 6th June 1915. From photographs he appears to have been a patient with some kind of leg problem (maybe the fracture of a limb through the fall of his horse) at Chelmsford in June 1916; and was then at The Hollies, Shortland, Kent in November 1916. In December 1916, he proceeded to Salonica, where he was attached to the 43rd General Hospital. It is possible that he also spent Christmas 1917 with the 1st Battalion The Queen�s West Surreys. Hugh then offered his services when volunteers for medical service in France was being called for, he was accepted and spent 6 months in France, returning to Glasgow to undergo an operation. He was thereafter on duty at the School of Military Instruction at Brentwood, Essex. Here he was seized with influenza, which developed into acute pneumonia, from which he died at Purfleet Military Hospital on 7 November 1918. Hugh was the husband of Jessie Stobo Simpson of Davaar, Blairforkie Drive, Bridge-of-Allan, Stirlingshire. His High School obituary states in part "Captain McLean was a close student of the history and the literary antiquities of his native city. His great interest impelled him to take an active part in the proceedings of the Old Glasgow Club, or Provand's Lordship Club, of the Eastern Medical Society, of the Archaeological Society, and the Bibliographical Society, of which he was one of the founders. To the meetings of these societies he lectured on subjects within their purview, and several of his contributions were subsequently printed. Particular mention may be made of an excellent paper in which he embodied the results of his research into the life and work of one of Glasgow's greatest typographers, Robert Urie, from whom it is said the great Robert Foulis learned the art of printing, and to whom due tribute had not been paid.� [Information sources: CWGC; 1918 Medical Directory; April 1919 Glasgow High School Magazine and family (The portrait photograph courtesy of family)]