Discovered wrapped in a plastic bag and hiding away in my Garage / Workshop in October 2017. A Eureka moment!
As it emerged from storage for over 60 years in the canvas bag (above). Limited corrosion so it must have been well oiled before being put away!
Assembled view (Note: Trades Testing Board stamps top right and bottom left)
Separated to show details of fit (hand crafted to ± 0.001 inch accuracy). Various holes were drilled, tapped and reamed.