Renowned British conductor Sir Edward Thomas Downes, CBE, has died at the age of 85, after travelling to the assisted suicide centre Dignitas with his wife.
He and his 74-year-old wife Joan, who was terminally ill, chose to end their lives at the Swiss centre, their family said in a statement.
According to the statement, the couple "died peacefully, and under circumstances of their own choosing".
Sir Edward had a 40-year relationship with the BBC Philharmonic Orchestra.
"Our father, who was 85 years old, almost blind and increasingly deaf, had a long, vigorous and distinguished career as a conductor," his family said.
"Our mother, who was 74, started her career as a ballet dancer and subsequently worked as a choreographer and TV producer, before dedicating the last years of her life to working as our father's personal assistant.
"They both lived life to the full and considered themselves to be extremely lucky to have lived such rewarding lives, both professionally and personally.
"After 54 happy years together, they decided to end their own lives rather than continue to struggle with serious health problems."
A Metropolitan Police spokesman said their deaths were being investigated by Greenwich CID, as assisted suicide is illegal in Britain under the Suicide Act.
At least 115 people from the UK have gone to Switzerland to die but, as yet, no-one has been prosecuted.