We fell foul of these rules when we lived in our flat, again, thanks to our neighbours. They reported our ‘monstrosity’ of a garden shed to the local council. Like most people, we didn’t realise planning permission was required for the shed because our home was a flat - all our neighbours with a house could put up a shed, but we couldn’t. We had to apply for retrospective planning permission, which was granted, but it was a shock to realise that the planning rules are so bizarre.
In some cases, PD rights are removed (an Article 4 Direction) from houses, such as those in a conservation area, so you need permission from the local council for pretty much everything externally. When we had a house with no PD rights, applying for permission was free of charge for most things. However, a lot of the local residents didn’t apply, probably because they didn’t realise they had to. Most got away with changing the appearance of their homes - as long as no one complained to the council.
On ‘designated land’, which includes conservation areas, the PD rules (where PD rights haven’t been removed) are different - planning permission is required for more things. For example, side extensions and loft conversions are not permitted development for houses on designated land, but they can be done without planning permission on most other houses, as long as the PD rules are complied with.
The rules are even stricter for listed buildings. If you want to make changes to a listed building, the safest option is to check with your local council’s conservation officers first, because even work that seems minor can require listed building consent from the council. The process of seeking consent is similar to that of planning permission. However, in complicated cases and ones involving certain types of work and Grade I and Grade II* listed buildings (these are the most important, but the majority have a lower, Grade II listing), the case will be referred to English Heritage. See www.english-heritage.org.uk for information on listed buildings.
You can appeal if consent is refused, but it may be a long and fruitless process. Trying to establish a good relationship with the council’s conservation officers before submitting your application is often a better approach, although they may not be open to negotiation. Doing unauthorised work to a listed building is a criminal offence (unless the work doesn’t require consent) and you can be forced to reverse any unauthorised changes. You can also be fined, so it’s not worth taking a risk.