Jan sent me pictures to identify the object and I was thrilled to see that it was an early Monarch floor spring housed in a box with handles attached. The handles were obviously attached for 'bench testing' and demonstration purposes, as is the perspex lid, thereby allowing prospective customers to quite easily see the 'action' of the Monarch when operated.
As can be seen from the pictures the internal parts have been highly polished and it appears that it has never had any oil in it.
I hope this blog post is an interesting talking point for you and your family and is dedicated to your late Father, Jan Snr.