Actually, just looked it up n my local council website:
"Whilst garden bonfires may have been a traditional method of disposing of garden wastes, burning garden waste produces smoke which contains carbon monoxide and toxic fumes. Most of us have neighbours living close by who may not share our enjoyment of a bonfire. Smoke can ruin a neighbour's enjoyment of their garden, prevent windows being opened and prevent them hanging out their washing.
These days it is not necessary to burn waste. You will find that nearby is a County Council local amenity site, where most waste items including cardboard, can be recycled or composted.
If you are bothered by smoke from a bonfire, firstly approach your neighbour and explain the problem. Immediate recourse to your Local Authority may cause animosity between you and your neighbour. Should this approach fail, it may be that the Environmental Services Division can assist. It is useful to keep records of the dates and times nuisance from the bonfires occurred.
Section 79 of the Environmental Protection Act 1990 refers to nuisances caused by smoke. It may well be that smoky bonfires could be a contravention of the Act if they occur on a regular basis, and prosecution may result. It is, however, the view of this Authority that most people are proud of their civic responsibility as they are of their own gardens, and will consider their neighbours before lighting a bonfire."
Seems they shouldnt be burning anything at anytime