Hattersly and Davidson power hammer

This is my 2cwt Hattersly and Davidson power hammer, made in Sheffield, England. I found it while on holiday in my first year of university in 1987. It was sitting outside an engineering shop in Whangerei (north of Auckland, New Zealand). Being a poor student, I couldn't afford to buy it until 1991, when it was still there. It cost $NZ200 (around $us100 at the time) and $400 to move it to Auckland.... it is sitting on a 2.5m^3 concrete base held down by 1m long 30mm bolts. The 2.75hp motor came out of a scrap yard. It hadn't been used for many years and had been sitting outside for at least 10-15 years when I got it. It was missing the treadle and the motor mounts, as well as the rotary connection for an oil feed along the length of the shaft to lubricate the clutch, and I made these bits up. An unusual part of the design is the way the main part of the frame is 6" higher or so than the anvil. It is supposed to be like this, according to the photocopy of the site plans and some instructions I got with the hammer. The length of throw of the crank is adjustable with a large screw in the crank. I was told it had originally been bought by the Kamo brickworks for making bricks (!) and was one of 3. Only 1 had been installed when the company went broke. The clutch leather had rotted and the flywheel had seized on the shaft. It sat outside my workshop for a further 2 years before it was finally installed. It stands around 7' 6" tall and weighs 2 tons or so. According to a bit of research from a contact in Sheffield, Hattersley and Davidson were a large conglomerate of companies in Sheffield, making a large variety of products, besides hammers and forging machines, and included Robert Sorby (of wood turning tool fame) after 1 934. They were broken up many years ago, and all that remains now under that name is a company making ice Skates(!) which changed it's name to HD Sports a few years ago. I don't know the age of the hammer, but I would guess at it being around WW2 vintage. Any information would be appreciated