Geoffrey Clough Ainsworth was a mycological scholar of distinction, with an unparalleled knowledge of the bibliography and history of the subject. An indefatigable worker and campaigner for all aspects of the mycological cause, his contributions to the documentation and internationalisation of mycology have had enormous and on-going influences.

Geoffrey was born in Birmingham on 9 October 1905, the only son of the Rev. Percy Clough Ainsworth. Educated at Ipswich Grammar School and Kingswood School in Bath, he proceeded to the then University College Nottingham, obtaining first class honours in botany in 1930. En route in 1929, he obtained a certificate in pharmacy and was awarded the Pharmaceutical Society's Silver Medal and Harrison Memorial Prize. He was then lured into plant pathology, first working as an assistant at Rothamsted Experimental Station from 1930–31, and then as a virologist at the Experimental and Research Station in Cheshunt, Hertfordshire, from 1931–39. The period at Cheshunt was an enormously productive one for Geoffrey. He took a particular interest in virus diseases of horticultural plants, on which he started to publish profusely, including the first of many contributions to Nature in 1936. At the same time he obtained a PhD from the University of London in 1934, and compiled his first book: The Plant Diseases of Great Britain (1937) – a bibliographic account of the different diseases caused by bacteria, fungi and viruses arranged by host.