Communities secretary Hazel Blears backed an appeal by Commercial Estates Group and Hallam Land Management against Durham City Council's refusal of 250 homes and 9,300m2 of employment space in Bowburn.
The council argued that it has five years' worth of housing supply and had allocated the site for prestige industrial use in its local plan.
NLP Newcastle senior associate director David Graham said: "This sends out a strong message that the secretary of state and inspectors are implementing PPS3 and honouring the commitments set out in the housing green paper."
He added: "It clearly confirms that district housing requirements are no longer to be regarded as ceilings."
NLP has also won permission for 4,000m2 of office space and a hotel at Waterloo Road in London, subject to a section 106 agreement.
For more details of the Durham case, please see DC Casebook, p26.