His early education was at Glasgow Academy and Glasgow University, graduating in 1937 in Mathematics and Natural Philosophy and winning the Logan Prize as the best Arts student of the year. Wishing to enter research in theoretical physics he went to Cambridge, then an outstanding world leader in physics. From 1937 to 1939 he took parts II and III of the Mathematics Tripos as a Scholar of St. Johns College, graduating and being awarded the Mayhew Prize. In autumn 1939 he started a brief three months as a research student of the thermodynamicist R.H.Fowler before the war supervened. He worked in the Admiralty scientific service from January 1940 to September 1945, first at Teddington and then at the Mine Research Department attached to HMS Vernon, Portsmouth. At both Laboratories Gunn worked in a group led by Harrie Massey first on counter measures to magnetic mines and later on design and development of a series of British non-contact mines. Massey first developed a high regard for Gunn’s abilities at this time; it may be remarked that this group included a number of young physicists who later contributed significantly to pure science, the most notable in that respect being Francis Crick. Apart from the operational research aspects, Gunn’s work involved much classical applied mathematics.