Very, very nice Raul. I figured that you had one of these MK IV Target .22RF revolvers and I wanted to see some siblings since I honestly don't know a lot about them. They only show up briefly in a few of my references and these don't get into any significant detail. I suspect that W&S didn't make too many, but then I have no idea of the actual production number. I do know that they were produced from 1929 until the mid 1950's.
The W&S Mdl 1911 ss pistol was originally manufactured as a trainer for the W&S Mdl 1906 .32 self loading pistol, and reportedly, one was issued to each precent of the London Metropolitan Police. W&S also continued to produce some Mdl 1911's as replacements, and for commercial sales, but the total number produced was apparently, less that a couple of thousand.
The long barrels on the two single shot pistols is probably intended to provide a longer sight radius, and perhaps for balance.
LDHare