Clearly we have a lot of conflicting information about Webley revolvers. I am not saying anyone is right or wrong but this area is very confusing. I just went to open the FRT (for what it is worth!) but the RCMP system is down right now.
I purchased a Webley MK V once as a restricted firearm, on close examination I realised the frame was a MK I, the serial number on the frame was on the side indicating a commercial model. There was another serial number(different) on the hinge of the barrel, indication a later military? model and she was clearly marked MARK V on the side of the top strap. There were no War Dept arrow head markings anywhere that I could find. I was later told that she had been verified by an RCMP member, clearly he did not have a detailed knowledge of firearms, as do most verifier's. I applied to have her classed as antique and she was approved as antique.
I know of other antique handguns that have been approved as antique but in my opinion they are not. I couldn't sell one of them with a clear conscience in case the new owner got into trouble.
Some manufactures assigned serial number blocks to different models or contracts, often not all these numbers were used,sometimes the manufacture went back and used these "spare" numbers at a later date, sometimes they didn't. A lot of manufacturers records have been lost over time so often it is impossible to say with any degree of accuracy the date of manufacture.
When I can open the FRT I expect to find some MK III list as prohibited, restricted or antique. I will report back when I have that information, but let me also add that I personal put no faith in the FRT as it is full of errors.
In all fairness to the RCMP and everyone else, new information about different firearms is always surfacing, there is always something new to learn, this is one of the most fascinating things about collecting and dealing in older firearms.