Dunlop Special Lightweight rims - Tubs or Clincher?

A picture of the OUTSIDE of the rim (where the tyre is seated) is what is required, instead of the picture you have offered.

Old style clinchers did seat differently to modern ones. The rims were less "lipped" also.

Yes, not the most descriptive image, only one I have to hand at the moment. These rims are definitely less "lipped"