Quick update for any interested parties/people stumbling upon this thread via Google searches:
10th of October conveniently marked 1-year to the day I last left his shop having finally completed the frame, so I sent one last round of warning/correspondence and predictably got no response.
Given that he had almost 2 full working days as a chance to reply but didn't, Trading Standards are now involved.
Since my previous comms with Paul, I've been contacted by 2 others in the same position and - looking at Google reviews - a 3rd appears to have also started the Trading Standards process against EB a fortnight ago.
Goodness knows how many others are out there who haven't publicised their situation with EB (yet) ...