The Farmer went out to check on the sheep this morning and found a cast ewe. From sheep101.com:
A sheep that has rolled over onto its back is called a "cast" sheep. It may not be able to get up without assistance. This happens most commonly with short, stocky sheep with full fleeces on flat terrain. Heavily pregnant ewes are most prone. Cast sheep can become distressed and die within a short period of time if they are not rolled back into a normal position. When back on their feet, they may need supported for a few minutes to ensure they are steady.
This ewe fits the bill on all counts: short and stocky breed, full-fleeced, and heavily pregnant.
Apologies for the poor quality of the photo. It's hard to take good quality pictures in the darkness of the barn, even when you are not in a hurry to right a cast ewe.
The good news is that she is fine. When telling me about this cast ewe, The Farmer said: "Roll them over and watch them run." We have not always had this good ending. It's harder on them in the hot summer sun. That's why it's important to check on sheep regularly.