The material is presented in the order given in the List of contents. It covers the period 1926-1999 but the bulk of the material dates from the latter part of Clarke's career.

Section A, Biographical, includes a number of autobiographical and biographical accounts, and there is significant material relating to honours and awards Clarke received. There are diaries including one from student days in 1926, but mostly dating from the periods from the late 1940s to the mid 1950s and from 1983 to 1996. There is a little family material, chiefly relating to his grandfather and father and their roots in Leicester. Also included is information relating to deposits of archival material and butterfly specimens elsewhere.

Section B, University of Liverpool, is very slight. It includes Clarke's account of the Department of Medicine 1958-1972 and his annual research reports to the University 1991-1998.

Section C, Medical research, is unfortunately not extensive. It does include documentation of Clarke's post-war research on nutritional deficiencies in British Prisoners of War. However, the bulk of the material dates from the 1980s and 1990s and relates to Clarke's post-retirement studies of longevity and pregnancy in diabetes.

Section D, Lepidoptera research, documents some of Clarke's work on butterflies and moths 1950-1998. Although there is a slightly better coverage of Clarke's work over many decades than in the medical research section, again the bulk of the material dates from the 1980s and 1990s. Topics included are work on Papilio dardanus and moth pheromones. There is also material relating to import licenses and permits to bring lepidoptera into the UK, 1952-1991, which provides some indication of Clarke's research interests over time.

Section E, Publications and lectures, covers both medical and lepidoptera work. The bulk of the publications material relates to work done in the 1990s but far from fully documents Clarke's prolific output even in that decade. The publications include autobiographical reminiscences, a few papers on lepidoptera and medical subjects and obituaries and memoirs of a number of colleagues including I.B. Sneddon, Lord Zuckerman and E.B. Ford. The section includes documentation of a number of public and invitation lectures delivered 1977-1998, some on the occasion of an award. There is also an incomplete set of Clarke's offprints.

Section F, Visits and conferences, cover only a few of Clarke's visits and conferences 1963-1995. The two largest single components are documentation of Clarke's visit to China as a member of a Royal Society delegation in 1978 and material from a visit to Fiji in 1981.

Section G, Societies and organisations, includes seventeen British national and regional societies. The best documented are the Association of Physicians of Great Britain and Ireland, the Royal College of Physicians (chiefly Clarke's Directorship of the Medical Services Study Group and then its Research Unit) and an informal visiting group known as the Medical Pilgrims. The bulk of the material is from the 1980s and 1990s.

Section H, Correspondence, has been subdivided, following Clarke's arrangement into four subsections. The first is correspondence with named individuals. This includes H.B.D. Kettlewell and U. Mittwoch. However, of particular note in this subsection are the sequences of correspondence with J.B.S. Haldane and J.S. Huxley in which the principal correspondent is not Clarke (although he features in the correspondence with Haldane) but his Liverpool colleague and friend P.M. Sheppard. The second subsection presents correspondence on specific subjects, chiefly lepidoptera and including in particular material relating to work on the moth Bison betularia.

The other two subsections present sequences of later correspondence 1994-1998 arranged alphabetically, and of shorter exchanges or single letters found loose.

Section J, Non-textual material, includes an extensive collection of glass and negative photographic film slides, chiefly of lepidotera, a small number of photographs and cine and video documentaries on the rhesus work of Clarke and P.M. Sheppard.

Arranged into the following sections:

• SECTION A BIOGRAPHICAL D36/A.1-A.105
• SECTION B UNIVERSITY OF LIVERPOOL D36/B.1-B.8
• SECTION C MEDICAL RESEARCH D36/C.1-C.23
• SECTION D LEPIDOPTERA RESEARCH D36/D.1-D.42
• SECTION E PUBLICATIONS AND LECTURES D36/E.1-E.73
• SECTION F VISITS AND CONFERENCES D36/F.1-F.17
• SECTION G SOCIETIES AND ORGANISATIONS D36/G.1-G.34
• SECTION H CORRESPONDENCE D36/H.1-H.112
• SECTION J NON-TEXTUAL MATERIAL D36/J.1-J.50

Cyril Astley Clarke was born in Leicester on 22 August 1907. He was educated at Wyggeston Grammar School and Oundle School and, after a short period at Strasbourg University to improve his French, he entered Gonville and Caius College Cambridge in 1926. He graduated from the Natural Sciences Tripos in 1929 and won a scholarship to Guy's Hospital Medical School. He graduated in 1932 and after a number of staff appointments at Guy's, in 1936 he joined a life insurance company. He received his Cambridge M.D. in 1937.

In June 1939 Clarke, a keen sailor, volunteered for the Royal Naval Volunteer Reserve and was on the outbreak of the Second World War was called up as a medical specialist. He was initially stationed at the Royal Navy's base at Scapa Flow in the Orkney Islands but in 1942 received a posting to North Africa. Clarke was posted back to the UK at the end of the North African campaign and in 1944 was sent to Australia.

On returning to the UK at the end of the war Clarke found work as a registrar at Queen Elizabeth Hospital in Birmingham and a few months later was appointed Consultant Physician at the United Liverpool Hospitals. In 1963 he was appointed Director of the Nuffield Unit of Medical Genetics based at the University of Liverpool and two years later was made Professor of Medicine. He held these posts until retirement in 1972. Following retirement Clarke served as President of the Royal College of Physicians 1972-1977, Director of the College's Medical Services Study Group 1977-1983 and Director of its Research Unit 1983-1988.

In addition to the Royal College of Physicians, Clarke served many medical organisations in various capacities. He was President of the Liverpool Medical Institution 1970-1971, Chairman of the British Heart Foundation Council 1982-1987 and Chairman of the British Society for Research on Ageing from 1987. In 1991 he was elected President of the Royal Entomological Society of London for two years.

After his return to the UK after the war Clarke was involved in studies following up the medical treatment of British Prisoners of War who had developed nutritional neuropathy from their time in Japanese Prisoner of War camps. However, his most important research achievement was his discovery of a method of preventing 'rhesus babies'. Rhesus haemolytic disease in newborn children resulted from incompatibilities between maternal and foetal blood. Giving rhesus-negative mothers an injection of antiserum following the birth of a rhesus-positive baby prevented the mother's immune system from producing antibodies against subsequent rhesus-positive babies.

This development, which had a dramatic effect in reducing infant mortality from rhesus disease, had been facilitated by the knowledge of genetics Clarke had gained through his work with butterflies. Originally a childhood hobby, his interest in butterflies was reawakened during his military service in Australia. On return to the UK he devised a method of 'hand-mating' Papilio machaon with certain other species which enabled systematic genetic studies to be undertaken. Philip Sheppard, who came to Liverpool as lecturer in genetics in 1956, encouraged Clarke to use this knowledge of genetics in the medical field of blood groups. Clarke noted the similarity between inheritance of rhesus blood groups and butterfly mimetic patterns and this led to the breakthrough in treatment of rhesus babies.

Clarke continued active research at Liverpool into haemolytic disease in infants and developed an interest in other genetically related medical issues including longevity, asthma and cancer of the oesophagus.

Although it had begun as a hobby, Clarke's research into lepidoptera included not only studies of Papilio machaon and mimicry. Another of his interests was the peppered moth Bison betularia and the relation between the prevalence of the carbonaria form and industrial pollution. In 1988 Clarke rediscovered a colony of Scarlet Tiger Moths (Panaxia dominula), originally established at the Wirral Way, West Kirby, Merseyside by Sheppard in 1961, and this enabled him to investigate population changes.

Clarke received many honours and awards. He was made a CBE in 1969 and in 1974 was knighted. In 1970 he was elected Fellow of the Royal Society (Buchanan Medal 1990). Clarke was a Fellow of a number of medical institutions including the Royal College of Physicians, the Royal College of Obstetricians and Gynaecologists and the Royal Society of Medicine (Nuffield Medal 1984, Gold Medal 1985). He received honorary degrees from many universities including Birmingham, Edinburgh, Leicester and Liverpool. In 1980 he received the US Albert Lasker Medical Research Award and the following year received the Artois-Baillet Latour Health Prize in Belgium. Clarke's work as a lepidopterist was recognised by the Linnean Medal for Zoology of the Linnean Society of London (1981).