Prior to 2001 (excluding monarchs) who was the only female to appear on UK currency?

Florence Nightingale (12 May 1820 – 13 August 1910) was an English social reformer and statistician, and the founder of modern nursing. Nightingale came to prominence while serving as a manager and trainer of nurses during the Crimean War, in which she organised care for wounded soldiers. She gave nursing a favourable reputation and became an icon of Victorian culture, especially in the persona of "The Lady with the Lamp" making rounds of wounded soldiers at night.

Florence Nightingale's image appeared on the reverse of £10 Series D banknotes issued by the Bank of England from 1975 until 1994. As well as a standing portrait, she was depicted on the notes in a field hospital, holding her lamp. Nightingale's note was in circulation alongside the images of Sir Isaac Newton, William Shakespeare, Charles Dickens, Michael Faraday, Sir Christopher Wren, the Duke of Wellington and George Stephenson, and prior to 2002, other than the female monarchs, she was the only woman whose image had ever adorned British paper currency.