[Lanrezac]

I think the British bought at least 75,000 .455 revolvers from Smith & Wesson in World War I. Some were Triple Locks with commercial serial numbers (".455 Hand Ejector First Model", IIRC), some were Triple Locks in a special serial number range (".455 Hand Ejector Second Model") and the bulk had the third lock and the ejector rod shroud deleted (".455 Hand Ejector Third Model").

Colts in .455 were strictly private-purchase guns. There were quite a few of those, but nothing like 75,000, I think.

The First and Second Model S&Ws, being Triple Locks, command high prices now. I don't think it would be any easier, or cheaper, to find a Third Model that had not been converted to 45 ACP than to find an unconverted Webley.

Conversion to 45 Long Colt was also possible, because of the longer cylinders in the Colts and S&W. That allows .455 to still be used. (This assumes the conversion was done by machining out the chamber steps in the .455 cylinder. If the .455 cylinder was replaced by a 45 LC one, I think you're out of luck.) I used to have a Second Model that had been converted that way. I didn't shoot it much because whoever had converted it had taken a divot out of the inside of one chamber.

I don't know what I'd look for if I wanted a .455 revolver. Just keep hunting for an unconverted Webley, I guess, preferably Mark V or VI - I believe they had slightly stronger cylinders. Mark Is are considered black powder only now, I think.