Lucy Birley, mum to the Roxy Music star’s four children, passed away while on holiday aged 58.
Days earlier her pal and fellow socialite Annabelle Neilson died aged 49.
The pair were both part of a London set that included fashion icon Isabella Blow, who killed herself in 2007.
It is not known how Lucy died.
“I’m much saddened and shocked by this tragic news of Lucy’s death”
Ferry, 72, tweeted yesterday: “I’m much saddened and shocked by this tragic news of Lucy’s death.”
Before marrying Robin Birley, stepson of the late Sir James Goldsmith, in 2006 she had a two-decade relationship with Ferry.
A family statement said: “Lucy Birley passed away whilst on holiday in Ireland, surrounded by her beloved dogs, Daisy, Peg and Daphne.
“Her husband Robin and her sons Otis, Isaac, Tara and Merlin are understandably devastated and ask their privacy is respected during this difficult time.”
During her relationship with Ferry, Lucy battled drink and drugs before going teetotal in 1993 following rehab.