It seems a french test pilot, Jean Franchi and then a british one Brian Walpole both both barrel rolled a Concorde during testing. From the pilot video below it's clear the french were quite familiar with this trick and eager to show their friends across the channel how it was done.
I've heard it said that this is a positive G manoeuver, and can be done with any aircraft, whether that is true I don't know because I don't pilot.
Concorde barrel rolls.
There is a rumor that it was also done during a retirement flight.
Edmund