It is the opinion of the local planning authority that the proposed first floor extension is not subordinate in size to the existing dwelling and its design, with a substantial gable to the front elevation, would also conflict with its balanced shape and appearance. The dwelling is prominently situated within the street scene and, by reason of the height and design of the proposed extension, the resultant building would appear as a discordant feature which would be detrimental to the character and visual amenity of the locality. Therefore, the development is contrary to Policies H/17 and EV/1 of the Borough of Local Plan (2004) and the advice given in the Council's adopted Supplementary Planning Guidance on House Extensions (2001) and Supplementary Planning Document, Leading in Design (2006). These seek to ensure that extensions to dwellings are compatible in scale and design with the original and other dwellings.