We got one proper egg this morning
! They are in an omlet cube which is power washed once a week. This is kept in an enclosed run that is built as a box (to stop foxes), with wood chip on the floor! Hubby and I work at home, so they free range in the garden all day whilst we are there. We have two labs who aren't bothered by them, and the cats got seen off by the chickens from the start!. So no, I don't think stress is an issue.
There is no history of illness, and although there are no outward signs of illness, I wondered if some sort of infection was causing it. I truly couldn't cull them, it would be too mean from my perspective. I'd have to let them live without earning a living then start again when they've all pegged it!
I will however, take your advice, see a vet and see if antibiotics will help. Thanks