OK, I know everyone probably getting a bit bored with this thread, but please bear in mind that I'm not having a happy time at this end either
so, 1 step forwards, 1 step back
I replaced the front wheel bearings tonight I was able to do it a hell of a lot faster than I did last time - so that's some progress! I also learnt from the previous mistakes about under tightening the adjuster nut when you first do it. so, I tightened it up as much as I could, then backed off, then just nipped up. everything went back in the same place.
I test drive it as soon as I'd finished, and the rattle is still there

It's the same as it was before I did the front bearing - well, more or less anyway. sometimes you can convince yourself that it feels slightly better, even when it's not.
So, It "feels" like it's coming mostly from the back... BUT the steering wheel still visibly shakes side to side. There's no strength in the shaking though, so perhaps it's just transmitting through the chassis?
I still haven't done the front radial arm bushes - but I'm working on the assumption that they wouldn't cause this symptom.
so, here's my options as I see it, please please please add to/amend if you have any thoughts:
1) rear stub axle could be worn
2) the new rear bearing could be ****ed after a couple of hundred miles of wobbling before the adjuster nut was done up.
3) front radial arm bushes are causing the shaking
4) A frame bushes in the rear are causing the shaking
5) SELL IT!
I'm convinced at this stage that options 3, 4, or 5

are valid... but please correct me if I'm wrong.
Thanks