Augusta's mother died soon after her birth. Her grandmother, Lady Holderness, raised Augusta for a few years, but died when Augusta was still a young girl, and the child divided her time among relatives and friends.
Augusta's half-brother, George Lord Byron, did not meet her until he went to Harrow School, and even then only very rarely. From 1804 onward, however, she wrote to him regularly and became his confidante, especially in his quarrels with his mother. Their correspondence ceased for two years after Byron had gone abroad, and was not resumed until she sent him a letter expressing her sympathy on the death of his mother, Catherine in 1811. Not having been brought up together, they were almost like strangers to each other. But they got on well together and appear to have fallen in love with each other. When Byron's marriage collapsed and he sailed away from England never to return, rumours of incest, a very serious and scandalous offence, were rife. There is some evidence to support the incest accusation. Augusta Leigh's third daughter, born in spring of 1814, was christened Elizabeth Medora Leigh. A few days after the birth, Byron went to his sister's house Swynford Paddocks in Cambridgeshire to see the child, and wrote, in a letter to his confidante, Lady Melbourne: "Oh! but it is 'worth while', I can't tell you why, and it is not an "Ape", and if it is, that must be my fault; however, I will positively reform. You must however allow that it is utterly impossible I can ever be half so well liked else-where, and I have been all my life trying to make someone love me and never got the sort I preferred before." "Ape" alludes to the fear that the child would be born deformed.
Later life
One of Augusta's daughters, Georgiana, married a cousin, Henry Trevanion in 1826, apparently at her mother's instigation; they had three daughters. Trevanion, who may also have had a relationship with Augusta herself, left Georgiana in 1829-30 for her younger sister Elizabeth Medora, who had been staying with them; Medora and Trevanion lived together for several years in France, before finally separating in the 1840s, Medora going on to marry a French soldier.
Poetic references
Augusta is also the subject of Byron's Epistle to Augusta and Stanzas to Augusta.