Originally Posted by Mr W martin
I accept that the tang may be original, but I would be amazed if the gun left the Webley factory with the KB engraved.I cannot offer any other idea and look forward to the true explanation. Richard Gallyon ( no longer connected with Gallyon Guns)has the records and I've always found him extremely helpful.
I really like Webleys , although I feel they are not the most pleasant guns you shoot.
Regards mr w martin

Asking about the gun in in other places indicates that it's probably a batch number, or possibly a custom order gun with the original buyer's initials.