Ladies of London star Annabelle Neilson has passed away at age 49.

People confirmed the model, socialite and reality star's passing on Monday, but did not report any further details on the circumstances surrounding her death. The Daily Mail has since reported Annabelle died in her home in Chelsea, London last Thursday and that the death is "not being treated as suspicious." The cause of her death is not known.

Annabelle was a staple in London's fashion scene who came from an aristocratic family. Prior to joining the original cast of Ladies of London, she was best known as the muse and best friend of the late, great British designer Alexander McQueen.  The pair were so close friends often referred to Annabelle as "Mrs. McQueen." Years after the designer's passing, Annabelle told the Daily Mail he indeed once asked her to marry him, but she declined. (The proposal was platonic; McQueen was openly gay and Annabelle served as a bridesmaid during his 2000 wedding to filmmaker George Forsyth.)

 

Annabelle Neilson and Alexander McQueen (Photo: Getty Images)

 

She appeared both on McQueen's runways and on his arm at parties, which is how she came to develop close friendships with the supermodels Kate Moss and Naomi Campbell. In London, Annabelle ran with a famous set of friends that included Sienna Miller, the artist Damien Hirst and the designer John Galliano. She became a bold face name herself when she married banking heir Nat Rothschild, the wild child son of the British lord Jacob Rothschild. The couple dated as teenagers after meeting on a beach in India, then eloped to Las Vegas in 1995. They split after three years of marriage.

Annabelle was the daughter of Elizabeth, the Marquesa Campus di Santinelli, and as a young girl she spent time at several of England's most famous estates, including Warwick Castle, home to her first cousin, the Earl of Warwick, and Mapperton, the Jacobean manor house often featured on Ladies of London.

 

Kate Moss, Annabelle Neilson and Naomi Campbell (Photo: Getty Images) 

 

Her introduction to most North Americans was via the first season of Ladies of London, which premiered in June 2014. With her links to nobility and fame, Annabelle brought credibility to the show, but she also charmed viewers with her dry wit and impeccable style. She used the show as a way to jumpstart her career as a children's author and to gain attention for her book series The Me Me Me's. Following her departure from Ladies of London, she told the Daily Mail, "The show has served its purpose. It has enabled me to get The Me Me Me’s off the ground and make a name for myself in America. I didn’t go into it to make friends."

The book was an outlet for Annabelle to write about her own difficult childhood, including her severe dyslexia; a learning difficulty she and Alexander McQueen both suffered from. Annabelle also faced incredible struggles as a teenager. As a 16-year-old she was attacked by a man while on vacation with her family in Australia; an experience that led to a battle with depression and drugs.

“After that, I fell into a serious depression and became a heroin addict because it provided an escape bubble and was the only way I could cope,” she told the Daily Mail.

Annabelle later gained sobriety, but she continued to face hardships throughout her life, including the loss of her great friends McQueen and Isabella Blow, the magazine editor and fashion icon who originally introduced her to McQueen. Isabella committed suicide in 2007, McQueen in 2010.

Just weeks ago Annabelle was pictured at the wedding of her ex-boyfriend Lord Edward Spencer-Churchill at Blenheim Palace alongside Kate Moss and the fashion designer Alice Temperley.