Erection of a rear roof extension; installation of 3no rooflights in the front roof slope and 1no rooflight above the main flat roof at roof level; erection of a rear extension at second floor level over part of the existing back addition; erection of a single storey rear extension to the side of the existing back addition; installation of bi-folding doors to replace the existing window at ground floor level to the rear elevation; excavation of part of the front and rear gardens to form front and rear lightwells, in connection with the enlargement of the existing basement; conversion of the existing single family dwelling house into 2no. self-contained residential units, consisting of 1no. three bedroom maisonette at basement and ground floor level and 1no. two bedroom maisonette at first and second floor level.