My records indicated that John Harper, the firm, made just under 1000 guns in their own name over a 75 year period (1902 to 1976). They included single barrel hammer guns, SLEs, BLEs and BLNEs in gauges 12, 16, 20 and .410 Of course, many more were made for the likes of Pape, Churchill, Boss (Robertson), Beesley, Wilkes, Woodward and Dicksons.
In the late 1890s there were 4 Harpers, all in the same family, making guns. John Harper I was a gun action maker. John Harper II started the eponymous firm in 1902; he died in 1937. By then his son John Norman Harper had taken over the firm. It was this last John Harper who became a Birmingham Gun Barrel Proof House Guardian; he died in 1981.
Tim