It is the opinion of the local planning authority that the proposed extension, by reason of its size, form, style, design, detailing and use of materials, would appear unduly dominant and incongruous in relation to the listed building and its setting and thus would be harmful to the character and appearance of this designated heritage asset and result in a development which is not of a high quality design. The proposal would lead to less than substantial harm to the significance of the designated heritage asset. In such cases, Paragraph 196 of the National Planning Policy Framework advises that permission should be refused unless it can be demonstrated that the harm is necessary to achieve public benefit that would outweigh that harm. The proposal is not considered to have such benefits. The scheme therefore fails the test for sustainable development as set out in the National Planning Policy Framework and is contrary to Policies CS2, CS14 and CS25 of the Charnwood Local Plan 2011-2028 Core Strategy, saved Policies EV/1 and H/17 of the adopted Local Plan, Policy T&C7 of the adopted Thurcaston and Cropston Neighbour Plan, the Supplementary Planning Document: Leading in Design and the Supplementary Planning Guidance on House Extensions.