Blue Plaques

KING, Ada, Countess of Lovelace (1815-1852) a.k.a. Ada Byron

Plaque erected in 1992 by English Heritage at 12 St James's Square, St James's, London, SW1Y 4RB, City of Westminster

Circular blue plaque to Ada King, Countess of Lovelace Oblique view in between iron railings of blue plaque mounted on white stucco wall

All images © English Heritage






ADA COUNTESS OF LOVELACE 1815-1852 Pioneer of Computing lived here



Ada, Countess of Lovelace, was a mathematician and computing pioneer. She has been called the world’s first computer programmer because of her work on the analytical engine developed by Charles Babbage, arguably the inventor of the computer.

Sketch drawing of a young woman in 19th-century dress, wearing flowers in hair and holding a closed fan
An 1839 engraving of Ada King, Countess of Lovelace. King saw the computing potential of Charles Babbage’s analytical engine, noting that it ‘weaves algebraical patterns just as the Jacquard loom weaves flowers and leaves’ © National Portrait Gallery, London


Born in Piccadilly, Augusta Ada was the only legitimate child of the poet Lord Byron. Her parents separated acrimoniously soon after Ada’s birth, and she was brought up by her mother, Annabella, née Milbanke, who supervised her education and encouraged her interest in mathematics and science. Annabella was apparently anxious that Ada should not grow up to be a poet like her father.

In 1835 Ada married William, Baron King, who was created Earl of Lovelace in 1838. In 1837 they moved into 12 (formerly 10) St James’s Square, where she remained until 1846. The house, which was built for the Lovelaces, is an early example of the Italianate style of Thomas Cubitt (builder of Osborne House on the Isle of Wight). Built of brick with stucco decorations, it forms a marked contrast to its more sober neighbours.


When she was 17, probably through the scientific writer Mary Somerville, Ada had met Charles Babbage, the inventor of the first general computer – a calculating machine or ‘analytical engine’. At once, she began to collaborate with him and mixed in his circle of friends and acquaintances, which included Sir Charles Wheatstone.

Ten years later, in 1843, while she was living at number 12, Ada wrote to Babbage:

I do not believe that my father was (or ever could have been) such a Poet as I shall be an Analyst; (& Metaphysician).

She had good reason to boast. She wrote the letter while adding extensive notes to her translation of an Italian paper on Babbage’s analytical engine. In one note, she proposed an algorithm for how the machine could compute the Bernoulli sequence of numbers – since described as the world’s first piece of computer code. Her contribution to computing is now widely acknowledged, and in 1979 the United States Department of Defense chose to name its new software Ada in her honour.

Nearby Blue Plaques

Nearby Blue Plaques

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