Capell was born in Northampton and educated at Bedford Modern School. He then studied the cello in London and Lille, before becoming a journalist. He served in France during the First World War; he was awarded a Military Medal for gallantry at the Battle of Vimy Ridge. From 1928 to 1933 he worked on the Monthly Musical Record, where, according to Grove's Dictionary of Music and Musicians, his abilities as an editor were evident.
In 1937 he took on the proprietorship of the journal Music and Letters, and he was its editor from 1950 until his death. During the Second World War he served as a war correspondent in France, the western Sahara and Greece for the Daily Telegraph. He was awarded the OBE in 1946.
Grove comments that Capell "was chiefly drawn to Schubert", and that his study, Schubert's Songs (London, 1928, revised 1973 by Martin Cooper), "established itself as an important book on the composer." His other books included Opera (1930, 2nd edition 1948). Several extracts from his notes for a study of Gustav Holst were published as articles in Music and Letters and The Monthly Musical Record.
He died in London in 1954, aged 69.
- "Mr. Richard Capell", The Times, 22 June 1954, p. 10
- Brown, Maurice J.E. " Capell, Richard", Grove Music Online, Oxford Music Online, accessed 23 April 2012 (subscription required)
- Blom, Eric. "Richard Capell", Music and Letters, October 1954, Volume XXV No. 4 (subscription required)
- "Music and Letters", The Times, 2 July 1954, p. 7
- The London Gazette: . 21 June 1946.
- "Capell, Richard", WorldCat, accessed 23 April 2012
- Music and Letters, April 1926, October 1926 and April 1927
- The Monthly Musical Record, 1 February 1927