Apologies, it has taken too long to post a pic but here it is.
You could try environmental health if they start burning stuff, depends where you live, it could be a smokeless zone. Any building in the garden has to be less than 2.5mtrs high from the highest point, but don't think councils can be arsed any more.
From next year the use of "wet wood" will be phased out for wood burning stoves, by wet wood, I think they mean unseasoned, and whether that contraption would come under the regulations I'm not sure. Every time they light it, complain to the council.These guys do burn stuff frequently. They chop up wood and use it to grill meat.
Pizzes me off when someone is red lining his motorbike,in his garage just for full sound effect.Very low tolerance for that caper.Had another bloke grizzeling from. Up the road at 3pm.one afternoon when I started up my Norton
Said he was eating his tea
Its been modified, so the 4/10 year rule and any certificate of lawful development may now been nullified. It should be enforceable.
https://www.legislation.gov.uk/ukpga/1990/8/section/171B
The four year rule applies to alterations and additions and changes of use to a single dwelling house. If the work involves a change of use to something other than a single dwelling house then the time limit for enforcement action is ten years.
Perhaps he's been cremated.but X has been quiet since.