Neil Ripley Ker was born in London in 1908 and educated at Eton and Magdalen College, Oxford, obtaining an honours degree in English language and literature in 1931. He completed his B.Litt. thesis on the manuscripts and palaeographical aspects of Ælfric's Homilies in 1933 and stayed in Oxford, beginning to give courses in palaeography in 1936.

At the outbreak of war in 1939, Ker, as a conscientious objector, was assigned to work as a porter at Oxford's Radcliffe Infirmary. From 1937, he had worked with Christopher Cheney, Richard Hunt, R.A.B. Mynors, and J.R. Liddell on a project to catalogue all surviving books from medieval libraries in Britain. Publication of Medieval Libraries of Great Britain (London: Royal Historical Society, 1941) was followed by Ker's appointment as University Lecturer in Palaeography. In 1945 he was elected to a fellowship at Magdalen College, and in 1946 he was appointed Reader in Palaeography. From 1955 until his retirement in 1968 he was Librarian at Magdalen College.

Medieval Libraries of Great Britain was revised and augmented in 1964, and a further supplement to the second edition, containing Ker's work from 1964, edited by Prof. A.G. Watson, was published in 1987.

In the early 1950s, the Standing Conference of National and University Libraries asked Ker to describe medieval manuscripts in collections then uncatalogued. Medieval Manuscripts in British Libraries appeared in 5 volumes. By the time of Ker's death in 1982, 2 volumes had been published (London, and Abbotsford-Keele). The third and fourth volumes (Lampeter-Oxford, and Paisley-York) were seen through the press by his literary executor, Prof. A.G. Watson in 1983 (Vol. 3), and Alan Piper in 1992 (Vol. 4). The final volume, of indexes and addenda, produced by Prof. Watson and I.C. Cunningham, was published in 2002.

Ker received honorary doctorates from the universities of Reading (1964), Leiden (1972), and Cambridge (1975), and fellowships of the British Academy (1958), the Medieval Academy of America (1971), and the Bayerische Akademie der Wissenschaften (1977). He was a gold medallist of the Bibliographical Society (1975). In 1979 he was appointed C.B.E.

Ker's publications include: