My query relates to an office to resi development approved under Class J of the GDPO 1995. The approval was for X dwellings; however, it has been completed with X + 1 dwellings (but within the same building envelope). The applicant now wishes to create an additional 2 flats (also within the building envelope) and apply for retrospective planning permission for the additional flat already built as well as the additional 2 flats.
Application was made as full planning permission. Council is refusing to determine as it says such changes cannot be made and that because the additional flat was built the existing use is not lawful and the applicant would need apply for full planning permission (from scratch) for the change of use from office to X + 3 dwellings...which seems ridiculous given that dozen of flats have already been built and occupied (95% or so in accordance with the plans and with no impact on external appearance). Commutative impact on transport/flooding/contamination is negligible (the Council even confirmed they would have approved the 3 additional dwellings had the applicant shown these on the plans back when they first applied).
My question is, can the changes be formalised via a full planning permission (part retrospective) for the creation of 3 additional flats? The GPDO clearly states that the development must be built in accordance to the prior approval plans unless agreed otherwise in writing. (source: http://www.legislation.gov.uk/uksi/2013/1101/article/6/made). Surely, a full planning application could be conceived as a form of written agreement?