W.J.Jeffery designed and produced a number of proprietry cartridges, as well as a number which were 'picked up' by the trade.

These include: .255 Jeffery, .275 Jeffery, .300 K Jeffery, .280 Rimless, .333 Jeffery Flanged, .333 Jeffery Rimless, .450/.400 3-inch NE, .404 Jeffery, .450 No.2, .475 No.2, .500 Jeffery Rimless, and the .600 NE.
Prolific, wouldn't you say?!!

His proprietry .475 No.2 ended up being different from the trade version. The jeffery round loaded 80gr cordite beneath a 500gr bullet of .489 dia. The trade version contained 85gr cordite under a 480gr bullet of .483 dia. MV and ME of the Jeffery cartridge were significantly lower than 'trade' ballistics.

The .400, .450 No.2, and .475 No.2 arose because Jeffery was concerned about the industry practice of loading smokeless cartridges which could fit into the old black-powder guns, with oft-disasterous consequences. He 'invented' stronger brass with thicker rims to circumvent this problem. When he developed the .600 NE (which was never a black-powder round), he simply stuck with the thicker rim etc for the new cartridge.

NitroX, your 'Indian Gentleman' is chambered for a Jeffery cartridge!!!

BTW, the best treatise on Jeffery's cartridge development is found in Wal Winfer's 'British Single Shot Rifles, Vol.3', a lengthy 39-page Chapter 5: "Cartridges Used in Jeffery Rifles". Great stuff!