The cut down rifle with cup he has listed isn't exactly what would be mounted to a carrier. But it would be good for passing beers around
The small cup launcher was for Number 68 A/T grenades and Number 36 fragmentation grenades when fitted with a metal gas check disc. But the seller does have the larger size smoke discharger what goes on a carrier in another listing.
The shortened Enfield with a grenade launcher was used in the original Star Wars movie as a prop weapon. Almost all of the weapons in the film were British or German WWI and WWII firearms with the exception of the postwar Sterlings. If you watch closely in the pre-digital remastered films, you can see the muzzle flashes and brass cases ejecting as blanks are being fired in the assault scenes. Lazer blasts got dubbed in with the muzzle flashes which helped tie in the effect of the people actually firing their weapons.
Attachments show two shots of the grenade launcher on shortened Enfield rifle, one of a British WWI Lewis Gun, and two shots of German WWI MG15s.