Lars, after your other superb find:-
Out of interest Eley were not the only one of them making cartridges that were for “Special” customers.
From Jim Buchanan, here is a pictures and some history on the Kynoch Magic cartridge.
And just to show that not only Eley did this - here is one from Kynoch that you will not find in a catalogue.
Brand of cartridges by Kynoch, Known in 12 and 16 bore with dark green tube and “KYNOCH NOBEL” headstamp. The Cwp. Includes the N.I. Volcano logo and “Magic shell/ Smokeless powder”. Box seen indicates “Loaded at the Kynoch factories of Nobel Industries England, for the Markle Warehouse Association. Houston and New Orleans”.
Jim, sorry I just had to edit out “shotshell”, what are you like. ;)