Per Cartridges of the World, the British military service cartridge known as the "450 Revolver/450 Adams" became a popular commercial caliber and "... both Colt and Smith & Wesson chambered revolvers for it. ... The 450 can be fired in any 455 Webley revolver, and it was often used as a light target load. ... Ammunition can be made from cut off 455 Webley cases."
I have never seen one marked "450 Eley", but from the above I would not doubt that some do exist.