Elizabeth Fortescue was one of the offspring of Sir Adrian's second marriage, to Anne Rede. One of her brothers was John Fortescue of Salden, who had been in Princess Elizabeth's service during the reign of her Catholic sister, Mary I, and proved a pillar of the Elizabethan regime and a persistent parliamentarian, later becoming Chancellor of the Exchequer. Her brother Anthony Fortescue, on the other hand, actually was a Catholic conspirator, closely involved with the Pole family. Another brother, Thomas, seems to have negotiated Elizabeth's marriage with Bromley, purchasing part of the manor of Holt from Anthony Bourne to settle on her in 1578.