I used to own that chopped up Purdey tube; where it went after leaving here I'm not quite sure!
The other one resembles the commercial model that Aldis tried to flog after WWII, if you please, using surplus parts and a new tube. Yours may be an earlier version as most of them have a cruder drum that appears to have been made for the purpose.
All in all, another example of the same old failure to invest in new products and innovations, with the inevitable result of corporate extinction.