On further investigation on the bottom of the clutch there is a label which reads, Warner Brake and Clutch and is rated at 90 volts 10 watts.
My father in law was an electrician by trade so the wires disappeared into the shed wall, but I followed it to a light switch then further on to a big green ac/dc voltage meter under that was a Rotary Regavolt dial, and isolated by a fuse switch.
By then I thought I had cracked it so I switched on the isolated fuse switch there was a pop inside the green voltage meter and a puff of white smoke, so I quickly isolated it again, whilst watching for any flames.
So at least I know why it was not revolving but can I fix it, I know the wires coming out of the green ac/dc were connected to the DC plug.
Why was this clutch in place, surely the Myford is safe enough without it, and how easy would it be to reverse the process.
Anyway thanks again for all the help, I have posted what I found in the gallery.