Dunlop Special Lightweight rims - Tubs or Clincher?

Right, so what kind of tyre would of been used with these rims to get a higher PSI?

There is no tyre which will allow very high pressures on old Dunlop/Endrick/van Schothorst rims. The whole point of modern hooked bead or* crochet *rims was to get over the problem of tyres blowing off the old style rims at high pressure.