Richard A.S. Redmayne was educated privately and at the College of Physical Science, Newcastle upon Tyne. After completing an apprenticeship in mining engineering he rose to under-manager at the Hetton Collieries in County Durham. He came to South Africa in 1891 to manage collieries and investigate mining properties in Natal, staying for 19 months. His visit led to an informative paper, "The geology and coal deposits of Natal", read before the North of England Institute of Mining and Mechanical Engineers and published in its Transactions (1893, Vol. 42, pp. 221-256) and as a pamphlet (36p, 2 maps). He thought that the coal measures of Natal were of the same age as those of the Stormberg, despite the dominant presence of Glossopteris fossil plants in the former. His paper included a discussion of the coal-fields of Biggarsberg, Dundee, Newcastle, and Impendhle, and he concluded that F.W. North* had overestimated the amount of coal in the Klip River district.
From 1894 to 1902 Redmayne was manager of the collieries at Seaton Delaval, Northumberland. In the latter year he accepted an appointment as professor of mining at the newly created University of Birmingham, where he applied modern American methods for training mining engineers. His department was the first in Britain to include an ore-dressing laboratory, and used a model underground coal mine for training purposes. In 1908 he was appointed chairman of a Royal Commission to study the causes and prevention of accidents in mines, and over the years served on a number of committees of the Mines Department to investigate and report upon explosions in coal mines. From 1908 to 1919 he was first chief inspector of Mines for the Home Office, and from then to 1935 chairman of the Imperial Resources Bureau.
Redmayne was an able administrator and speaker. He was honoured as a Companion of the Order of the Bath (CB) in 1912, and as a Knight Commander of the Order of the Bath (KCB) two years later. In 1916 he served as president of the Institution of Mining and Metallurgy, and in 1934-1935 as president of the Institution of Civil Engineers. He published many journal articles and several books, including the five-volume Modern practice in mining (1908), Methods of working coal (1914), and the autobiographical Men, mines and memories (1942).