Partial demolition and rebuilding of the front and rear facades, demolition and rebuilding of the third floor level, erection of a part single, part two storey upward extension, rear extensions at ground and first floor level and part rear extensions from second to fifth floors to provide additional office (E(g)) floorspace, plant with enclosure at roof level, roof terrace at 5th floor level, new lift core, internal alterations and new street elevation lightwell.