Sub-division and conversion of 36 existing units into 54 flats (creating 19 new units) including change of use of 1 unit to office (Use Class B1); reinstatement of original 'open' nature of enclosed stairwells by removal of roofs, glazed curtain walling and external walls and relocation and installation of windows and external door openings (30-32 even, 38-40 even, 45-75 odd, 103-105 odd, 111-113, 117, 125 and stairwells at 30-44, 45-75 and 101-131 Chevington; 10, 24, 28, 36, 58, 62, 66, 70 and stairwells at 10-40 and 42-72 Hopedene; stairwells at 10-40 and 42-72 Rennington; 53 Hendon Road and 47 Edgeware Road)