I've picked up a bunch of pre-war Threepersons holsters by S.D.Myres over the years. In many sizes from snubby to 6+ inches. They are always works of art.
I don't have all my pics here with me in hospital but the trusty Campbell example is probably one of the best. He even had the matching spare round holder. He used it for both his working Reg Mag and for his weekend fancy off-duty Non-Reg. The other pic is of Campbell wearing the rig and working gun at Quantico circa 1938.
Hope you enjoy.
Dave