Thankyou Martha. Unfortunately all 3 remaining pullets now showing early symptoms. I highly doubt it is cocci given that there is no blood in stools, they are still eating as and when they can potter about until the late stages. Nothing environmental has changed they have been here with me for 4 weeks and by the time they became ill they were totally settled, eating well and roosting at night, the other hens had accepted them.
Will have to chalk it down to bad luck I guess and just be careful where I buy my stock from in future, luckily I do not sell my hens on they are with me for life and don't hatch chicks anymore so that is something I guess. I have a few ex commercial hens that I think are vaccinated against it but in the same respect they are running with 6-10 unvaccinated birds which I hatched out here so would have been pullets too last year. to all who have taken the time to comment today it's much appreciated.