Certainly should say on top of the bbl., by patent dates if Colt or Smith & Wesson made the gun.
Just answere a query yesterday over on the Colt Forum, about the approximate # of .455 New Services made for the Brits in 1915-1916. Unlike S&W, Colt did NOT use a separate serial number range for their "special contract guns".
Best estimate we can figure is at least 55,000 Colt New Services for the Brits in .455. Unless they were a special, private order of a British officer, the British Colts all left the factory with bright blue finish, 5.5" bbls, and the standard, black "hard rubber" stocks and lanyard loop.
S&W made about 5,000 of the famed Triple Locks for the British, starting a separate serial # range at "1" (in addition, about 650-700, were quickly converted from .44 Special, and are in the "regular" N frame serial range. This model is known as First Model Hand Ejector .455.
Next, S&W made just under 70,000 of the 2nd Model Hand Ejectors, withoud the Triple Lock and the under barrel "shroud" for the ejector.
BOTH S&W models were "originally", high polish blue", wood grips, with inset "gold" medallions, lanyard loops, and in 6.5" bbls.
These revolvers that were "exported back" to the U.S. in the 50's and 60's, to be sold as surplus, tend to have "many proof marks", and show nicks and dings from the anti-handgun English just "tossing" most of them in wood crates for the "boat ride back here"
Dealers here converted many S&W and Colt .455's to .45 Colt and .45 acp(and NOT always "skillfully" either!). In addition, especially the Colts, will be found frequently rebarrelled and recylindered into "non .45/455 calibers".
Living in Maine, I have been fortunate enough to get Canadian Colt & S&Ws .455's, and they are nearly always in far nicer condition, "non converted"; the .455 Colt cartridge, as made for many years by Dominion CIL of Canada, was a fairly powerful round for these guns.
Bud