Although MK VI .455 grips of Bakelite came in a couple of thicknesses, they were the same design. It was the Enfield No. 2 that had at least three types or styles of grips, and some were checkered; some grooved. The big ones were usually plastic, with a magna shape and built-in thumbrest.
The best made Webleys like the WG models and the ones made for Wilkinson Sword Co. had hand-honed actions and very bright blued finishes. The walnut grip panels often had a gold oval in one for the owner's initials. They were premium models made largely for sale to officers, who bought their own sidearms until 1920. To be sure, officers who didn't come from affluent backgrounds often bought the service models or similar ones, like the Webley Army model. It looked a lot like a MK VI with a rounded front sight like those on the MK I-V guns. Quite a few bought Colt New Service models or similar S&W's. And by WWI, a surprising number bought Colt .45 autos. Winston Churchill was among them.
But this has nothing to do with those MK IV .38's. BTW, those I've handled didn't have heavy, rough actions. Maybe I was lucky? The Enfield .38's do often have heavy actions, and many are DA-only. Tank crews complained about the hammer spurs catching on things, so instead of simply making the holster a litle deeper, they adopted a new spurless hammer.

They had open-topped holsters. Had they simply gone to the regular Pattern M-1937 holster, those had flaps that would have prevented the problem and they lie closer to the body and are less in the way than is the tanker holster. Trust bureaucrats to mess things up in every country.
As far as I know, no Colt, S&W, or Webley guns had the hammer spurs altered.