Colin Brian Haselgrove (1926-1964, known as Brian) studied mathematics at King's College, Cambridge (BA, 1948; PhD, 1950?), to which he was appointed a Fellow in 1950. Interested particularly in number theory, he became engaged in work on computational approaches at the University of Cambridge's Mathematical Laboratory using the EDSAC 1 machine. In 1956 he co-authored a paper on digital computing as applied to stellar evolution with the cosmologist Fred Hoyle. In 1957, Brian Haselgrove was appointed to a senior lectureship at the University of Manchester, with responsibility to promote mathematical computing. In 1958 he published the paper for which he is best remembered, demonstrating the existence of a counter-example to the Pòlya conjecture; computations underlying this work were performed on EDSAC and on the Mark 1 machine in Manchester. Brian Haselgrove remained active in teaching and postgraduate supervision until shortly before his death from a brain tumour in 1964.
In 1951 Brian Haselgrove married Jenifer Wheildon Brown (b. 1930) of Newnham College, Cambridge. As Jenifer Haselgrove, she was an EDSAC user from 1953 to 1956 as a member of the Radio Group of the Cavendish Laboratory. She is best known for the application of Hamiltonian methods in ray tracing, lending her name to the Haselgrove equations widely used in radio physics. During this period Jenifer Haselgrove was attached to the Nuffield Radio Astronomy Laboratories, Jodrell Bank.
John Anthony Leech (1926-1992) was an undergraduate alongside Brian Haselgrove at King's College, Cambridge (BA, 1950) and proceeded to work on digital computing at Ferranti in Manchester, returning in 1954 to the Mathematical Laboratory at Cambridge. His work focused largely on computational mathematics in the areas of number theory, group theory and geometry; he is noted for the Leech lattice in packing theory. In 1959 Leech moved to the Computing Laboratory at the University of Glasgow. Jenifer Haselgrove and John Leech, who had known each other at the Cambridge Mathematical Laboratory, married in 1965. Jenifer (who appears as 'Jenifer Leech' in most subsequent correspondence, though some later published work appears under the Haselgrove name) also moved to work in computer science at Glasgow. In 1968, John Leech moved to head the Computing Science department at the newly-founded University of Stirling, where he remained, gaining a personal chair in 1970, until his retirement in 1980. Jenifer Leech remained at Glasgow until 1982.