Born in Ealing in the United Kingdom on August 4, 1908, he received his Doctorate in Physics from Imperial College of Science and Technology in London in 1937. He did graduate work during the 1930s in Copenhagen and Berkeley. While at Berkeley he worked with E. O. Lawrence on the cyclotron in the Radiation Laboratory and was the discoverer of the radioisotope gallium-67 (Physical Review 54, 649, 1938), which is still in use in nuclear medicine. His mentor at Imperial College was G. P. Thompson the British physicist in charge of the Tube Alloys project during the war years (the British nuclear program that was later incorporated into the Manhattan Project). He had Mann assigned to the British Embassy in Washington and to the Chalk River Laboratory in Canada. In 1951, Wilfrid Mann came to the National Bureau of Standards as the head of the Radioactivity Section. For the next 30 years Wilfrid Mann was the most influential radionuclide metrologist in the world. During the early 1950s, he had a keen interest in the national standards for radium-226 and undertook microcalorimetric experiments to intercompare the national standards (Hönigschmid standards) of the United States, United Kingdom, Canada, and Germany. He retired from NBS in 1980. His several texts include Radioactivity and Its Measurement, 1980 (Mann, Ayres, and Garfinkel), A Handbook of Radioactivity Measurements Procedures, NCRP Report 58, 1985 edition, and Radioactivity Measurements: Principles and Practice, 1988 (Mann, Rytz, and Spernol).