The St Helen's House complex consisted of the house ('A'-block), which contained classrooms and offices; an attached annexe known as the Pearson Building ('B' Block), which held most of the classrooms on the ground and second floor plus on the first floor 'Big School', the school's large assembly hall complete with stage; there originally was a free standing school chapel, which was demolished in September 2017 to make way for new housing development called Kings Terrace; plus a separate building in red brick which housed the Chemistry Department approached through the cloisters between the rear of 'B' Block and the Laboratory. In this corner of the buildings was the Headmaster's House built around the late 1880s. When the house became vacant and following the development of the OTC/JTC/CCF this was converted into an armoury containing scores of weapons - dozens of Lee–Enfield .303 rifles, several .303 Bren Guns with tripods, a couple of handheld Sten guns and revolvers. No live ammunition was stored. Originally in the rear playground there were then several single-storey prefabricated wooden buildings which contained the woodworking classroom, gymnasium, changing rooms and shower facilities, the reason they were built of wood was because the main GNR / LNER railway lines from Ilkeston and Nottingham to Derby Friargate Railway Station went underneath in a 'cut and cover' tunnel. Approached off Edward Street there was a smaller annexe originally part of a Junior School where the refectory dining room was along with some classrooms.