Some breaches of planning control aren't breaches unless an event has happened on more than a set number of days in a year,for example, over 14 days in the case of a motorbike-scrambling event outlined below.
You need to record on how many days the activity has taken place since 1 January of that year.
However, if the problem is large advertising hoardings alongside a major road, you should pinpoint the location as clearly as possible and the company whose product is advertised.
For example, for the 'change of use' of a building to a dwelling house or the felling of protected trees, the time limit is four years after the operations were completed. After this period, the development automatically becomes lawful.
You should look at the local authority register to see what enforcement action has been taken, because evidence of a longstanding breach can also help strengthen your case.
Last year, the peace of our summer weekends was repeatedly shattered by the noise of motorbike scrambling in a nearby field. The landowner has advertised more scrambles for this summer. He says that he doesn't need planning permission. What can we do?
Events including motorbike scrambling and markets are classified as 'permitted development' and can take place on the same site for up to 14 days a year, without any need to apply for planning permission. Also, land can be used for up to 28 days in total in any calendar year for any other type of use.
Any 'moveable structure' can also be provided on the land if it relates to any of the temporary events mentioned that are taking place.
Keeping account of the number of days used is a major headache for planning authorities, especially if events take place at weekends when council staff aren't around.
It's a good idea for you to keep a record of activities, to help councils to keep such events within the proscribed limits.
Also, if you can find demonstrable evidence of engineering work or a permanent structure having been erected to serve the temporary use, that would prevent the land returning to agricultural use, then the development should be subject to full planning control.
'Engineering work' or 'permanent structures' have been held in relevant court cases (see Ramsay v Secretary of State for the Environment, Transport and the Regions  EWHC Admin 277).to include jumps, the creation of banks, and the erection of crash barriers. If you spot anything like this on the site, you should let the local planning authority usually the District / Borough Council know as soon as possible.
If the trial affects a footpath or bridleway, The Road Traffic Act 1988 (section 33) also states that a trial between motor vehicles, including motorcycles, is an offence unless the trial is authorised by the highway authority, again, usually the County Council or District / Borough Council where there is no county council, and the consent of the owner is obtained in writing.
CPRE is aware of cases where the highway authority did not act against an unauthorised scrambling event affecting a footpath, on the grounds that it could not establish the persons responsible.
It is therefore well worth doing what you can to establish who is responsible for the event, in order to help the highway authority to enforce the law.
Alternatively, you can lobby the authority to serve an injunction against 'persons unknown'.
For further advice on using legal processes, you should contact the Environmental Law Foundation.
Environmental Law Foundation
Suite 309, 16 Baldwins Gardens,
Hatton Square, London EC1N 7RJ
Tel: 0330 123 0169
If the development does require full planning approval, you can scan the Local Plan or Local Development Framework for your area on relevant policies on open space, landscape, leisure development, tranquillity and the area in question.