SADLER, Flora Munro, n. McBain, born Aberdeen 4 June 1912, died Aberdeen 25 Dec. 2000. Mathematician and astronomer. Daughter of Isabella Webster, domestic servant, and John McBain, dairyman's carter.

Flora McBain graduated with honours in physics and mathematics from the University of Aberdeen in 1934. She held posts there from 1934 to 1937 as demonstrator in medical physics and then as lecturer in applied mathematics, while researching into radium sources for cancer treatment. With her professor, J. A. Carroll, she took part in a successful expedition to observe the total eclipse of the sun in Omsk, Siberia (19 June 1936). In 1937, despite being advised initially that a woman had little chance, she was appointed to a post at the Nautical Almanac Office, becoming the first woman scientist to hold a senior post (eventually Principal Scientific Officer) at the Royal Observatory, Greenwich, of which the Nautical Almanac Office was part. In 1949, the Observatory moved from Greenwich to Herstmonceux in Sussex where she worked until her retirement in 1973. Apart from during the Second World War, when the Almanac Office carried out special tasks for the Services, Flora McBain's work involved the computation of astronomical and navigational tables, her special field being the motion of the moon and the prediction of eclipses of stars. Her work, entailing international collaboration in which she represented Britain, had wider significance in determining the variation in the rotation of the Earth and the establishment of time. The first editor of the Royal Astronomical Society's professional journal, she was also the first woman secretary of that society, from 1949 to 1954, the year she married her colleague Donald H. Sadler (1908—87), Superintendent of the Nautical Almanac Office, in what was described as ‘the astronomical romance of the decade’. MTB

• ODNB (2004) (Sadler, Donald); Tayler, R. J. (ed.) (1987) History of the Royal Astronomical Society, vol. 2, 1920—1980; Wilkins, G. A. (2001) ‘Flora Munro McBain 1912—2000’, Astronomy and Geophysics, 42.4, p. 34.