Augusta Byron, later Augusta Leigh (1783 - 1851) was the only daughter of Captain "Mad Jack" Byron, the poet Lord Byron's father, by his first wife, Amelia d'Arcy, Baroness Conyers in her own right, the divorced wife of Francis, Marquis of Carmarthen, who was later to become 5th Duke of Leeds.

Augusta's mother died soon after she gave birth and it was her grandmother, Lady Holderness, who raised her for a few years. Her grandmother died, however, when Augusta was still a young girl and she in turn divided her time among relatives and friends.

Augusta's half-brother, George Gordon Byron, didn't meet his sister until he went to Harrow School and even then only very rarely. From 1804 onwards, 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.

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 suddenly sailed away from England never to return, rumours of incest were rife. Incest in those days was a very, very serious and scandalous offence; and some say it was because of his fear of prosecution that he abandoned his country.

There is some evidence to support the incest accusation. For instance, the Honourable Augusta Leigh's third daughter, born in the Spring of 1814, was Christened Elizabeth Medora Leigh. A few days after the birth, Byron was at his sister's house Swynford Paddocks, Six Mile Bottom , Cambridgeshire, to see the child he appeared to believe was his. In a letter to Lady Melbourne, his confidante, he wrote: "Oh, but it is not an ape, and it is worth while". (A child of an incestuous relationship was superstitiously thought likely to be deformed).

"Medora" is the name of one of the heroines in Byron's poem The Corsair, which was written at Newstead Abbey during the three weeks in January 1814 when the poet and a pregnant Augusta were snowbound there together. Augusta's husband, George, however never questioned the paternity of Medora, and she grew up among her brothers and sisters blissfully unaware that she might be the first of Byron's three daughters.

In fact, they were entertained by his in-laws at the family home in Leicestershire for several weeks after Byron had married Annabella Milbanke. At that time Augusta wrote to her sister-in-law about Medore saying: "The likeness to Byron ... makes her very good-humoured". In another she wrote meaningfully, knowing it would be shown to Byron, "Here comes Medora".