Ashley, who says she's written thousands of letters to transgender, gay and lesbian people over the course of 50 years, says she knew she would be pioneering a dangerous operation when she decided to undergo sex reassignment surgery in Morocco in 1960, despite being told that there was only a 50/50 chance of survival.
"However, I knew I was a woman and that I could not live in a male body. I had no choice. I flew to Casablanca, and the rest, as they say, is history," Ashley, 77, writes on her website.
According to the BBC, Ashley was outed as transgender by the Sunday People in 1961, a revelation that left her "humiliated in front of the world," she says.
Bella Jay, director of the charity Sparkle, says Ashley "played an important role in bringing issues into the public eye and campaigning for equal rights."
Her divorce from Arthur Corbett in 1970 grabbed headlines after a judge ruled that she was still a biological man, despite her surgery, and that her marriage was invalid and annulled. The decision was precedent-setting for transgender people until 2004, when the Gender Recognition Act allowed people to legally change gender.