This is a change of use from industrial to residential. The garden city principles are meant to ensure there is a balance between industrial and residential development to meet the needs of working people in the town and encourage as many people in Letchworth as possible to work in the town in which they live. Increased development of housing at the cost of industrial land means that people will put extra pressure on the surrounding transport infrastructure (already creaking at the knees) and risks Letchworth becoming a dormitory town. There is little enough decent affordable office space in the town (The Spirella building is stupidly priced at £24 psf) with enough parking (The Nexus building has inadequate parking)