John Leech, after graduating from King's College Cambridge in 1950, worked at Ferranti's in Manchester on early digital computers. In 1954 he left Ferranti to return to Cambridge, becoming a research student in the mathematical laboratory. He was appointed as a lecturer in the Computing Laboratory of Glasgow University in 1959.
He spent the academic year 1967/68 as a research fellow at the Atlas Computer Laboratory.
He edited Computational Problems in Abstract Algebra , the Proceedings of the first Atlas Symposium held in Oxford in 1967. The volume contains thirty-five articles by some of the world's leading experts on the use of computers in abstract algebra.
In 1968 he was appointed as Reader and first Head of Computing Science at Stirling University. Two years later he was promoted to a Personal Chair, the first awarded by the University of Stirling. He took early retirement in 1980, having worked part-time for a few years before this due to ill-health.
John Leech was a pure mathematician, with a taste for number theory, geometry and combinatorial group theory, his interests tending towards the particular rather than the general. He developed one of the first programs to implement the Todd-Coxeter coset enumeration algorithm - a pioneering achievement in the application of computers to algebra. He is best known for the Leech lattice which gives rise to three sporadic simple groups.
He was one of the most avid supporters of the preservation of the paddle steamer Waverley. John Leech collapsed and died on the 28 Sept 1992 on board the ship during the final cruise of the season. He was standing between the funnels on the return leg between Rothsay and Largs when he suffered a heart attack. As the steamer made its way back up river to Glasgow, the red Ensign was lowered to half mast as a tribute.
