Sorry to inform you that last night the chicken took a turn for the worse. Breathing became a problem and started shaking and twitching and unable to hold her head up.
Took her to the vet, who agreed that the best thing was to put her to sleep, she had got considerably worse by the time we had got there. So she's no longer with us, and will be popped under a tree in the orchard, along with all our other ex-animals just as soon as the ground softens up a bit. However, I think the chicken had the last laugh, it cost me £28.90 at the vets!