Just for interest, there's a short note on one of my Mk.IVs on the 'Newsletters' page of our local Arms Collectors Club website: ACANT Website
Scroll down to the December 2007 issue at the bottom of the page: click on "Enigmatic 'War Finish' Webley"

BTW Riley, we mainly use Fiocchi .455 cases: perhaps not 'pukka', but practical!