OK. I've done a bit of digging and, based on that and what you guys have told me, this is my revised game plan:
1: Soak negs in water for 5 mins.
2: Bleach neg back to base in pot ferri/pot bromide/water (2:1:some). NOT farmer's (thanks chaps)
3: Expose to strong light source (not quite sure what this achieves, but have seen it referenced in a couple of sources, and can't see the harm. Anyone any ideas?)
4: Wash.
5: Redev in PMK (Ole: I'm not ignoring the pyro/soda solution - can't get pyro before weekend. Will try as soon as I can. Sounds like an interesting mix.)
I found a thread by Gainer on the AZO forum. "...There's no need to worry about development times or agitation, as it should go to completion. There is, of course, only enough silver bromide left to restore the original silver image, and once that is done the staining stops because the developer needs the local products of reduction to form the mordant to fix the stain. Consequently, there is no danger of overdeveloping, and streaking or bromide drag can only occur if development is too short."
So, does this sound reasonable? Please let me know if you see any errors, and I'll let you know the outcome.
Many thanks
Geoff