Rear infill extension at lower ground floor light well, replacement of existing dormer roof, lowering floor of vaults and lower ground floor, creating new steps within the front lightwell, new rear French doors to rear courtyard at ground level, part replacement and refurbishment of windows, replacement rear roof light and new roof hatch to central valley and internal alterations, all to alter single family dwelling house (Class C3).

Variation of condition 1, condition 4 (parts a, d, e, g, h, I, j, k) and condition 5 (parts i, iv, v, vii, viii, x) and the removal of condition 4 (parts b, c, f), 5 (parts ii, iii, vi and ix) and 8 of listed building consent dated 3 December 2020 (RN: 20/03709/LBC), which itself varied Condition 1 of listed building consent dated 3 April 2018 (RN: 17/10530/LBC) for 'Alterations to the existing building including removal of existing roof top plant and extension to create an additional storey at fifth floor with tiled mansards and lead clad dormer windows to front and rear; a single storey extension at fourth floor comprising a glazed dome above the existing rear bow; installation of plant at roof level; partial infilling of lightwell adjacent to Gwydyr House; facade cleaning and other facade repair; internal alterations including reconfiguration, fabric removal, and refurbishment works on all floors; refurbishment of meetings rooms, entrance reception and offices; installation of new heating and cooling equipment; provision of a glazed research pod in the library; installation of light-boxes above the central stair and library, and other associated works'. Namely, to allow amendments to the approved scheme that include the installation of a proposed smoke extract system to mechanically ventilate new smoke lobbies to the secondary staircase; the removal of the lift access to the new fifth floor level and associated rooftop overrun; internal alterations at fourth and fifth floor levels; and alterations to ducting at roof level.

Amalgamation of the ground and first floor maisonette, with the second floor flat, the third floor and part of the fourth floor penthouse to create a single family dwelling house, creation of separate self-contained four bedroom flat at fourth floor level (accessed via 19M Hyde Park Gardens). Demolition of existing extension at ground and first floor, installation of replacement windows at ground, first, second and third floors, demolition of crittal doors and terrace at fourth floor and roof level, erection of mansard roof with dormer windows and parapet, demolition of roof access and rendered chimney and erection of lift motor room at roof level. Internal alterations and refurbishment, including the reinstatement of original features throughout including fireplaces and joinery details, reinstatement of spiral stair from lower ground to third floor, demolition of lowered ceilings, removal of a twentieth century stair and addition and removal of partitions (linked to 20/08322/FULL).

Variation of condition 1 of listed building consent dated 3 April 2018 (RN: 17/10530/LBC) for 'Alterations to the existing building including removal of existing roof top plant and extension to create an additional storey at fifth floor with tiled mansards and lead clad dormer windows to front and rear; a single storey extension at fourth floor comprising a glazed dome above the existing rear bow; installation of plant at roof level; partial infilling of lightwell adjacent to Gwydyr House; facade cleaning and other facade repair; internal alterations including reconfiguration, fabric removal, and refurbishment works on all floors; refurbishment of meetings rooms, entrance reception and offices; installation of new heating and cooling equipment; provision of a glazed research pod in the library; installation of light-boxes above the central stair and library, and other associated works'. Namely, to vary the approved drawing numbers to make amendments including a reduction in size of the glazed dome and automatic opening vent, increase in size of the plant area, omission of a rooflight bay and internal alterations.

Excavation of a basement under footprint of the house and part of front and rear garden incorporating lightwells, demolition of existing rear conservatory and erection of a single storey glazed rear extension, removal of rear dormer and erection of new dormer window, installation of replacement rooflights, replacement/repair of windows, rebuilding of existing timber shed, installation of vehicular gates, installation of an air conditioning unit at the side of the building, and general internal/external refurbishment works. (Linked to 20/03115/FULL)