Elizabeth Violet Maconchy was born on 19 March 1907. The second of three daughters of Violet Mary, née Poë (1878–1940), a homemaker, and Gerald Edward Campbell Maconchy (1875–1922), a solicitor, Maconchy's birth took place at the family's home at Silverleys, St Catharine's Estate in Hoddesdon, Hertfordshire.

Of her paternal lineage, Maconchy's roots can be traced to Scotland. Sometime in the late seventeenth century, a move to Ireland took place, with Maconchy's ancestors eventually settling in the county of Longford. According to records published in 1878, Maconchy's grandfather, George Maconchy (1818–89), possessed 10,319 acres, making him one of the largest land owners in the county. After receiving his Bachelor of Arts from Trinity College, Dublin in 1838, George embarked on a career as a solicitor, later serving as a magistrate in the counties of Longford and Wexford, as well as High Sheriff for the county of Longford in 1846. In addition to a home in Rathmore, North Longford, the family also owned a home called Edenmore in Raheny, Dublin, as well as a home called Corrinagh in Torquay, Devonshire, where George relocated his family around the latter half of the 1850s. After the death of his first wife, Louisa Elizabeth Richards (1824–64), with whom he had had ten children, George married Janet Hamilton (Campbell) Middleton (1835–1910) on 2 July 1867.

Gerald, who was the youngest of Janet and George's children, was born on 21 June 1875 in Torquay. He spent part of his childhood living in Clifton, Gloucestershire and was later sent to Charterhouse school, where he boarded at Pageites House. In 1894, Gerald matriculated at Trinity College, Oxford, graduating with a 4th Class Juris and Bachelor of Arts in 1897. In 1901, he passed his qualifications to become a solicitor, basing his practice in London. Given his familial ties to Ireland, Gerald appears to have visited the country with some frequency. A keen amateur golfer, in the summertime he often took part in amateur golf tournaments.

Of Maconchy's maternal lineage, Violet was the eldest of four children born to George Leslie Pöe (1846–1934) and his wife Mary, née Caldecott (c. 1855– 1924).’