I have this old Tom Senior M1 mill, which started life at the Winfrith atomic energy facility back in 1959. Have been told it’s a dual spindle type and is very rare. The head is similar to an S, but is driven by a second spindle near the top of the column, and doesn’t have its own motor like the S head. Just wondering if anyone has seen anything like this at all? It runs very smoothly but is in need of cosmetic work obviously and some of the chromed parts need re-plating.