The proposed mansard roof, by removing a pitched roof of architectural importance and replacing it by a more dominant mansard roof, would be harmful to the special architectural character and historic interest of this Listed Building and harmful to the character and appearance of the Thurloe/Smith Charity Conservation Area, contrary to policy set out in Chapter 4 of the Unitary Development Plan, in particular Policies STRAT6, CD25, CD48, CD52, CD53, CD58 and CD38.