[warrenscott]

Any advice please?
One of my Chickens has taken to sitting in the nesting box all day and all night. I'm having to lift her out in order to get her to eat and drink which she then does happily. 10 mins later she is back in the nesting box (not sitting on an egg).
Although she is 'mid-range' in the pecking order normally, the other chickens have started getting at her whenever they can.

[ehs284]

Sounds as if she's broody. Do a search on this forum and you'll find lots of suggestions as to what to do, but no guarantees. It can be a real problem, although often it is the broody one who is aggressive it upsets the other hens. They do "come right" but it can take months for our bantams to decide to go back to normal.

[ANHBUC]

Does sound like broody behaviour which is a blessing if you want to raise chicks and a pain if you want eggs.