Picked mine up for a case I have at a mil fair years ago it was either tarted up after the fact or fired at extreme range given the lack of damage to the projectile as a whole.
It shares a spot with its mate another smoke round this one was de activated and never fired as the driving bands have not been engraved by the rifling of the barrel also was the 20Pdr only used in the Centurion or was it utilised as a field piece as well.
Lastly for those that have the knowledge here would a smoke round make up a combat load for the tank I understand supporting the troops but it wouldn't it take up room meant for H.E & A.P just curious.