I was contacted by Chris Duke of CD Property Care about repair and service to the internals of a Sceptre No 21.
The internals were sent to me and I was surprised to find that the Sceptre was different to the Sceptres I have in stock as can be seen below (Chris's Sceptre is on the right). Both the carriage/yoke differs and the piston is a more 'squat' version (This may be because Chris's is the single action variant).