The development will consist of the conversion of 3no. flats back into a single family dwelling to include: demolition of non-original extension (at mezzanine level) to the rear return and the subsequent construction of a flat roofed single storey extension to the side and rear (5.8 sqm) and a part flat roofed single storey (5.3 sqm), part two storey (1.8 sqm) extension to the rear with a balcony, external staircase and platform lift providing level access to the garden. Modifications to the existing house; at basement level to include provision of new opening in rear wall to the new extension, provision of new opening in side wall to new extension, provision of new openings in the rear return walls to the new extensions, widening of existing opening to the front reception room, removal of 4no. modern windows, the reconfiguration of partition walls and the provision of a new staircase from ground floor level to basement level; at ground floor level to include removal of all modern partitions, modern doors and modern steps, replacement of sliding sash window to the rear reception room with new french doors, provision of new opening in the rear walls to the new extension, provision of new opening in rear return wall to new extension, widening of opening between the main reception rooms, lowering of floor level locally in the rear return, removal of modern window in rear return and blocking up of non-original window to the side; at mezzanine level to include removal of modern door on landing and replacement of door with new arched window reinstated to match original detailing; at first floor level to include removal of modern half level floor and modern staircase, modifications to doorways, blocking up of doorway into new walk in wardrobe and provision of new partitions; repair & re-pointing works to facades, repair & re-slating works to roof, repair work to the chimney, repair & repainting works to original windows and removal of bars at basement level, repair works to reception level ceilings and repair & restoration works to the granite entrance steps including the addition of a step at the base and associated site and drainage works, all at no.40 Leeson Park (Protected Structure), a 3 storey semi-detached building.