Born in Lemsford, Hertfordshire, in 1898. Grandaughter of Edward Lloyd, founder of Lloyd’s Weekly London Newspaper. Coggin grew up in the seaside town of Eastbourne, England. Educated at Wycombe Abbey school, which she left in 1916 to take up war work and eventually became a nurse at Eastbourne Hospital. After World War I, she resumed the social activities expected of a young woman of her class, but also worked for the Guides and the blind. In 1935 she published her first novel for girls, Betty of Turner House, using the pseudonym Joanna Lloyd (her mother's name). It was followed by five more girls' books. Between 1944 and 1949, she published four detective novels under her birth name featuring Lady Lupin Hastings, then wrote no more for 30 years before she died in 1980 at the age of 82. Her long out-of-print, and now very rare, detective books were reissued by Rue Morgue Press between 2001 and 2003.