Elizabeth was the daughter of Frederick Hervey, 4th Earl of Bristol (d.1803), and was familiarly known as 'Bess'. In May 1782, Bess met the Duke and Duchess of Devonshire, and quickly became Georgiana's closest friend. From this time, she lived in a menage a trois with Georgiana (d.1806) and her husband, William Cavendish, 5th Duke of Devonshire (d.1811). Lady Elizabeth married the Duke in 1809, three years after the death of Georgiana, styling herself Elizabeth Cavendish, Duchess of Devonshire. The Duke died two years later.
From 1816 until her death in 1824, Elizabeth Cavendish, moved permanently to Rome. She emulated her father in her new career as a liberal patron of the arts, and of archaeologists in particular. Her splendid palace in the Piazza Colonna was open to artists and statesmen alike and her final years were spent in the company of Cardinal Consalvi. The Duchess' real interest lay in Rome's archaeological antiquities: for eleven years she financed the excavation of the Forum. In unearthing the column of Phocus she was credited with the discovery of the pyramid of marble steps on which it rested. The city of Rome recognised her efforts with a medal struck in her honour. She died in Rome on 30 March 1824. Her stepson, William Cavendish, 6th Duke of Devonshire (d.1858), with whom she had a closer relationship than her own children, travelled to her bedside on news of her illness and as excecutor of her will distributed her treasured possesions to those she thought would appreciate them most.
Valadier, the papal architect included a drawing of the column of Phocas - showing the marble steps excavated by Elizabeth - in his Raccolta delle pi/au insigni fabbriche di Roma antica.