It appears to be good news.
The hives are reasonably heavy, there was a little activity and some grey pollen (willow?) was being brought in.  Under the outer cover I could see a nice tight cluster in the middle of the hive.
So it looks good!  If I manage to get to see them during a nice warm snap I'll consider feeding them, but right now I'll
leave them alone.  They know what they're doing!