Thanks Barry,
Tuning now seems stable after being strung up for 24hours, which is a very good sign.
Unfortunately she had been stored in one of the worst ways for many years..
2 strings on one side dramatically overtightened, resulting in neck bow & twist, + its pulled a slight bubble up in the top at the bridge.
There was also quite a low spot irrespective of the other problems in the neck between the 14th & 18th frets from shrinkage.
She was wearing a nut fashioned from a rough piece of plastic with 5 unevenly spaced slots & no saddle.
Everything is now back where it should be after weeks of fettling & she really shines.
Action is now spot on, with room for later adjustment if needed.
Next few weeks will be crucial, however, but so far so good.