Elinor Mary Monsell was born in Limerick, Munster, Ireland, the eldest daughter of William Thomas Monsell (1843–1887), a magistrate and inspector of facturers, and Elinor Vere, daughter of Hon. Robert O'Brien, of Old Church, Limerick (son of Sir Edward O'Brien, 4th Baronet).
Elinor Mary Monsell was born in Limerick, Munster, Ireland, the eldest child of William Thomas Monsell (1843–1887), a magistrate and inspector of manufacturers, and Elinor Vere, daughter of Hon. Robert O'Brien from Old Church, Limerick (son of Sir Edward O'Brien, 4th Baronet).