That large block at the spindle end suggest its a D1 series camlock spindle not screwed. My heavy 10 had a D1 and the spindle end looked very similar. Off hand I can't think of any screwed spindle fittings that look like that. From that angle you would probably see the threaded spigot of the driver plate which is about the only remotely similar candidate. If so more likely to be a 13" than a Heavy 10. Large dial D1 – 4 spindle Heavy 10's almost always had the wider range gearbox, 7 positions on the first lever I think not 5, and came on a cabinet stand.
The 13" never got a cabinet stand. Telling the difference from photos is very hard but Heavy 10's tend to look short from that sort of angle. Looking at pictures of mine its barely two apron lengths between centres. Checked the parts book and later 13" did get the D1- series camlock spindel
Its later than 1942. Especially if a Heavy 10. In that era a Heavy 10 would have had small dials, a single tumbler gearbox and star wheel feed clutch.
Clive
Edited By Clive Foster on 20/02/2017 16:58:03