I was just going to post that that looked an awful lot like the civilian Mk II in .380, not the .455 caliber military Mk II, which is an entirely different gun.
Yes, I think most of the Mk II's had the squared off butt, but as someone once said, "Webley made a mistake once and produced two guns alike."
An exaggeration to be sure, but it is hard to get a handle on all the variations of their basic models, not to mention the confusing duplication of "Mark" numbers for both military and civilian guns.
Jim