I just popped out into the Run to give them their afternoon treats, and there was an egg on the Run floor.
I know that Lydia laid in the Nestbox, so the floor layer must be Scarlett. This means that all three have laid today. Lydia, who looks like the biggest hen (she isn't, it's all fluff), laid the teeniest egg.
Here they are from Left to Right: Delilah, Scarlett, Lydia, 20p.