After marrying William King in 1835, Ada became known as Lady King. She married William, 8th Baron King, on 8 July 1835, when she was 19, and initially took the courtesy title associated with his barony.
The couple had three children and lived between estates including Ockham Park in Surrey, Loch Torridon in Scotland, and a London residence. Ada’s title changed again in 1838, when William was created Viscount Ockham and Earl of Lovelace; she then became Countess of Lovelace, the title most closely associated with her historical identity.
A common mix-up is to use “Lady Lovelace” for the entire period of her marriage. “Ada Lovelace” is also a later, familiar form: she was born Augusta Ada Byron and became Augusta Ada King after marriage. Her work with Charles Babbage’s Analytical Engine was published under her married name and initials.