MacCarthy was born in
Clonmel,
County Tipperary,
Ireland, the daughter of Dr. Charles William MacCarthy and his wife Marion. Her early years were spent in
Sydney, Australia, where the family emigrated in 1885. However, by 1891 she had returned to Britain to study the violin at the
Royal College of Music, London, as a pupil of
Enrique Fernández Arbós. As a child, she performed in standard concertos at the
Crystal Palace and
Queen's Hall. She also toured with the
Boston Symphony Orchestra, and visited
South Africa and
Australia. In 1905, she was forced to give up her ambitions as a concert soloist by the onset of
neuritis and went to
India as a companion of
Annie Besant, where she studied Indian music, collecting manuscripts and instruments, learned Indian singing and also studied Indian
mysticism. She returned to England in 1909 following the death of her younger brother. In 1911, she married William Mann, a fellow theosophist, thus changing her name to Maud Mann. The couple had a daughter, Joan, in 1912. The marriage was short-lived, as Maud soon met and fell in love with the composer
John Foulds in 1915. Despite strong opposition from family and friends, Maud and John Foulds left their respective spouses and lived together from 1918 onwards. They had two children, John Patrick (1916–2009) and Marybride (1922–1988). They finally married in 1932. She compiled the text for his
World Requiem which was performed at the Albert Hall on four consecutive Armistice Nights between 1923 and 1926. ==Spiritual teaching==