If changes are minor, these count as "permitted development" which means that they do not need permission. In some circumstances, permitted development rights can be removed by a local planning authority by using an Article 4 Direction.
This means that certain minor works such as replacing windows or front walls would need planning permission. The local authority might do this to prevent the character and appearance of a conservation area from being eroded through lots of changes which, although insignificant in their own right, collectively can have a large impact.
Some planning applications will include works which affect historic buildings or places, some of which may be protected, and the local planning authority will have to take into account the effect of the proposed development on what is significant about them.
Local planning authorities must consult Historic England on certain planning applications which affect the historic environment and where they intend to grant consent. This gives Historic England the opportunity to comment on applications at an early stage.
Details are set out in Historic England's Charter for Advisory Services.