Joined the Choir Invisible 

Refers to someone who has passed away. From George Elliot “O May I Join the Choir Invisible”. It is not something Monty Python invented!

She worked herself to death and has now joined the choir invisible.

Joined the Choir Invisible by Dutch Dirk December 19, 2017

Joined the choir invisible 

another term used to describe someone who's died, as first used in the "dead parrot" sketch of Monty Python.

He's run down the curtain and joined the choir invisible

Joined the choir invisible by Co-stanza August 31, 2010