The "Lucy" who inspired this song was Lucy O'Donnell (later Lucy Vodden), who was a classmate of John's son Julian Lennon
when he was enrolled at the private Heath House School, in Weybridge, Surrey. It was in a 1975 interview that Lennon said "Julian came in one day with a picture about a school friend of his named Lucy. He had sketched in some stars in the sky and called it Lucy In The Sky With Diamonds."
The identity of the real Lucy was confirmed by Julian in 2009 when she died of complications from Lupus. Lennon re-connected with her after she appeared on a BBC broadcast where she stated: "I remember Julian and I both doing pictures on a double-sided easel, throwing paint at each other, much to the horror of the classroom attendant… Julian had painted a picture and on that particular day his father turned up with the chauffeur to pick him up from school."
Confusion over who was the real Lucy was fueled by a June 15, 2005 Daily Mail
article that claimed the "Lucy" was Lucy Richardson, who grew up to become a successful movie art director on films such as 2000's Chocolat
and 2004's The Life And Death Of Peter Sellers
. Richardson died in June 2005 at the age of 47 of breast cancer.