Are You Considering Buying a Grade 2* Listed Building?
ANY works that may materially affect to the importance of the listed building requires listed building consent. That means inside and out! If you carry out works that require listed building consent without getting it it is a criminal offence!
There are no hard and fast rules on what would and wouldn’t require consent as what is considered important varies from building to building. I can only advise that you speak to the conservation officer at your local council