Augusta is a woman with short, dirty blonde hair. When using the persona Guy, she wears a fake moustache, beard, and wig. She is motivated by ideals rather than money, and behaves in a disdainful and condescending manner to everyone and everything, including the law.
Augusta orchestrates and participates in the bombing of The Simulacrum auction, which kills 17 people and injures another 24. Immediately after the explosion, she grabs something from Edison's corpse and escapes through a hole in the floor.
The Rangers meet 'Guy' in Other London in episode 14 at the Serpentines' base. They manage to take her down before she can do them much harm, and take her captive. They take her into custody with Sergeant Haringay, and during her interrogation in episode 17 discover her true identity as Lord Byron's half-sister Augusta. She viciously hates Byron, and, according to her testimony, seeks to destabilise everything he stands for. She also gives information on Jeremy.
The party meets Augusta again in episode 195, where she is working with Tesla, Babbage, and Lovelace on a solution to the infection. In episode 196, we learn that most of the items in the group's armoury were stolen for them by her.
Augusta Leigh is the real-life half-sister of Byron, and aunt of Ada Lovelace.