I found this entry on broadwayworld.com, and Rupert verified it was true when I asked him in London after a Dear Evan Hansen show.

Rupert was one of six vocalists in a production of Jacques Brel Is Alive and Well and Living in Paris at the Landor Theatre (over the Landor pub) in Clapham, London.

The show ran from 25 March to 17 April 2004, as part of the London Fringe.

• Director: Linda Edwards
• Cast: Marie Daly, Carys Gray, Kiara Jay, Stewart O’Reilly, Joseph Wicks, Rupert Young

While broadwayworld.com lists the production as also touring to the Southport Arts Centre, and Unity Theatre in Liverpool, Rupert says they were different productions, and he was only involved in the London show.