Listed Building Consent is required to demolish a listed building or to alter it in a way that affects its character as a building of architectural or historic interest. Thus, for example, if you are carrying out minor alterations to a modern extension to a listed building that is unlikely to require Listed Building Consent. However, if you are proposing to do works to a listed building which might possibly affect its character speak to your LPA to find out whether you need to make an application for Listed Building Consent.
When a Planning Department considers whether to grant or to refuse an application it must have special regard to the desirability of preserving the building, its setting and those features which make it special. Listed status covers a whole building, inside and out. Common works requiring consent might include the replacement of windows or doors, knocking down internal walls, painting over brickwork or altering fireplaces.
Listed Building Consent is administered by your Local Planning Authority (LPA). You can download an application for Listed Building Consent from your LPA’s website. Advice and guidance can also be obtained by looking at Guidance notes for Listed Building Consent on the Government's Planning Portal website. There is no fee for making a listed building application.
Certain essential works may be covered by a national or local Listed Building Consent Order, or owners and the LPA may enter into a Heritage Partnership Agreement setting out works for which listed building consent is granted (excluding demolition). More details on these recent changes are set out via this link.
There is also the option to apply and obtain a Certificate of Lawfulness for Proposed Works to a listed building (which is valid for 10 years) which confirms the works your are proposing would not require Listed Building Consent.
More detailed advice on Listed Buildings can be accessed here.