The implementation of The National Planning Policy Framework (NPPF) places greater weight upon the preparation of Statements of Significance for Heritage Assets and determining the potential impact (if any) of development on the setting of those assets.
Your Local Authority may request the preparation of a Heritage Statement or Heritage Impact Assessment. The purpose of such a report is to establish the significance of the buildings or sites that you wish to alter. The report is then used to inform you as the owner, those participating in your proposed scheme of work (e.g your architect), and your planning authority.
You may be asked for a Heritage Impact Assessment of any proposals on the significance and/or setting of the asset or indeed of any asset(s) in the immediate area that may be affected by your proposed scheme.
Each case is different and an early consultation is highly recommended in order to help identify any potential design solution and minimise impact at the beginning of the planning process.