Some time ago, she started disappearing for an hour or two each morning and - a most suspicious sign - wouldn't come running along with the others during feeding time. This made me suspect she is stashing her eggs in some secret spot, but as much as I tried, I never could track her to it.
Then one night she didn't come to roost, and I was worried - but next morning she re-appeared with puffed-up feathers, a characteristic clucking voice and an overall deranged broody hen look - not something I would expect in January, but there you go.
I did a thorough detective job watching her for an hour or two while I sat outside in the sunshine with my crochet work. Then she began walking away, and I followed - to her hiding place inside a bush, where I found a clutch of 16 (!) eggs.
Normally we wouldn't think of raising chicks at this season, but since she went to so much trouble, and since we'd love to get chicks from that set of parents (both gorgeous), we fixed a nice safe protected place for the broody in the coop and transferred her with all her eggs during the night.
In the morning I discovered that she had abandoned the eggs and went to back to her old (now empty) spot.
I picked her up again and, this time, locked her with the eggs in a secure cell. She clucked indignantly for a while, but then seemed to understand what is expected of her and settled on the eggs. It's amazing how such a little hen can contrive to cover so many eggs and keep them all warm.
She has been sitting all day now. We are hopeful.