BS for Star Delta starters

Well it might be fun to ask what British Standards a modern star-delta box needs to meet, and then see if this unit fails the technical requirements of that - I'd be surprised if the standards of the day when it was made are still current, but that does not mean the thing is instantly dangerous, but more of a 'treat with caution'.
If you really do mean pre-war then the ideas of earthing of power circuits (recall that  2 pin unshuttered power sockets were OK at that time) was much more sketchy that it is today, and the level of what would now be called IP rating was not really defined. You may need to add an earth terminal or two and some strategic mesh or other guard over any finger sized holes.

Do you have any pics of the internals ?

Mike

Hey presto.................................

Any ideas about the twin windings in the coil??

Oddly I replied last night and it is not showing. I'll type again, but this is necessarily terser due to time of day

It looks like there may be a kick-off winding on each contactor in series with the main winding on its neighbour - if and only if the winding handed-ness is correctly captured in the drawing. If that really  is what it is is showing then the idea is to ensure break before make. (and to have something acting like a transformer secondary winding whose voltage   tells you the core has pulled in.) However there is also stuff happening with the auxilliary contacts on L2 B2 A1 that is not entirely clear, so there may also be a hard pull-in (short fat winding) soft hold (long thin winding) type arrangement changeover in there as well.  Again this is to ensure sharp switching.

It is not really the clearest  diagram in that respect.

Mike.