Elizabeth Jemima was the daughter of Joseph Blake of Ardfry, Co. Galway. On 25 January 1790 she married George, 16th Earl of Erroll (b.1767), the eldest son of James, 15th Earl of Erroll and his second wife Isabella, daughter of Sir William Carr. George, who served as Lieut-Colonel of the 1st Guards at Walcheren, committed suicide on 14 June 1798 on a point of honour, having inadvertently disclosed a secret entrusted to him by Pitt. His brother William succeeded as 17th Earl. Elizabeth married secondly the Rt. Hon. John Hookham Frere. She died on 17 January 1831.

An earlier miniature portrait of the Countess by Cosway was engraved by Dean in 1841 (see Daniell's catalogue raisonné of prints after Cosway, 1890, no.68); this shows the sitter in a similar position, but with several differences.