Well some very good news!
Cable arrived, upgraded from firmware version 4.1 (original?) to 4.23, calibrated and today did a trim flight. About 07:30 but I had woken up anyway and it was really calm, virtually no wind, while the forecast was for wind and rain later. Go for it I thought.
Totally different bird. She still wants to tip while in "Stability" mode on the ground during spool up but I understand that is normal.
Once in the air there was a little drift to the right but two clicks of trim and there she was, hovering beautifully.
I only flew a couple of batteries as the wind started picking up. Let's see how I get to like her now.
Thanks for your help guys, especially Toad. Cheers!