Gunn offered his services to the Committee in November 1939, via Sir Robert Hutchison. He received three commissions: in August 1940 (IWM:ART LD 764), November 1949 (IWM:ART LD 997) and January 1941 (IWM:ART LD 5932). All were priced at 35 guineas.
Details of the subject of IWM:ART LD 764 are at (3)
There is also some post-war correspondence.