Hi David/Mair,
I'm no longer involved with armeria, though I still have both the plants I mentioned in my original post all that time ago. I don't think I'll ever get to the bottom of it though Rafa did put me in touch with a very good monograph on the species. I've looked all over the net, including the page you signposted me to David. That plant looks a lot like one of the ones I photographed, but still does not agree with the description in the botanical monograph. They really are a nightmare to sort out, so I thought I'd just leave it. Also got rust on the foliage of one or two and decided I didn't want to harbour more disease so they've gone now. Good luck to you Mair, send me a pm and I'll point you to the botanical work! Cheers