http://www.ruleworks.co.uk/poultry/allotments_uk.htm
Abolition of contractual restrictions on keeping hens and rabbits.
12. --(1) Notwithstanding any provision to the contrary in any lease or tenancy or in any covenant, contract or undertaking relating to the use to be made of any land, it shall be lawful for the occupier of any land to keep, otherwise than by way of trade or business, hens or rabbits in any place on the land and to erect or place and maintain such buildings or structures on the land as are reasonably necessary for that purpose: Provided that nothing in this subsection shall authorise any hens or rabbits to be kept in such a place or in such a manner as to be prejudicial to health or a nuisance or affect the operation of any enactment.
(2)...
Supplementary
You lease your land, your arent a poultry trader or running a poultry business, that leaves health and nuisance.
The council cannot rule that more than 7 birds if a health risk or a nuisance, only a court could, and they arent going to prosecute, because unless you actualy do keep your chickens in poor conditions, they will almost certainly lose.
Its always best to avoid legal action of course, but dont be afraid of the jumped up social worker.
My local housing authority was recentloy forced to back down in a case like this, but over 3 hens.
Dominic, your post is wrong in a number of regards and is dangerously misleading in stating the legal position.
Firstly, I have amended the quote you made of s.12, as s.12(b) was repealed by a 1973 Act.
Secondly, the council does indeed have powers under the environmental health (statutory nuisance) provisions to determine whether there is a statutory nuisance and, if they are satisfied that it exists, they can serve an abatement notice.
For example, they are perfectly within their powers to determine, having inspected the site, that more than 7 hens will constitute a statutory nuisance, and issue a notice accordingly. As I said previously, now that the council EHO has inspected and determined the facts (i.e. that no cockerels or ducks are present), they make an independent decision - and in a way, the details of the original complaint (and its validity) are no longer of as much relevance.
Breach of an abatement notice is an offence and can lead to a prosecution.
Thirdly, the environmental health inspector is not a "jumped up social worker". An EHO will be a member of the Chartered Institute of EH. Nothing like a social worker.
All that being said, HF is correct that there is much to be lost and little to be gained by uktitan trying to go to court, nor risking a council (?) tenancy over.