Having just typed all this, before posting it I made a call to our previous (3 years ago) insurers and have probably got the answer. But I'll post it anyway as it might be of interest.
"I've at last got to a stage where we can contemplate going abroad - to visit daughter in Singapore. Eye surgeon doesn't want to see me for 6 months, and I can walk normally(ish) again). It's been 2 years since we dared think about it or have a holiday between many eye treatments.
The issue is: who do you people do about your holiday insurance? (aged 70). The pre-existing conditions bit worries me. Having PMR isn't the worry, there won't be an emergency that can't be dealt with by some extra Pred before getting home. But what happens if GCA comes on as an emergency? Do you have medical cover for that - is it considered to be a part of pre-existing PMR?
Or does everyone just go and hope for the best (not very good at that! - could be an expensive emergency.) I'd be grateful for any recommendations. I do still feel I want to be somewhere with a good medical system nearby, so rural Africa for example is sadly out.
Got to find out also if my recent bunch of Glaucoma treatments is a worry, but nothing's likely to happen there in a hurry. Wife's previous BC has always been excluded from cover, but again there wouldn't be an emergency."
So - result of 'phone call and carefully explaining everything, Staysure say that for £26 extra they can cover need for treatment of the pre-existing conditions. Total for a year for both of us worldwide is £168.48, including gadgets e.g iPad.
Can I stop worrying?! Have another couple of companies to get quotes from.