This paragraph prevents diversification of industrial sites. If Harborough needs to attract more industry, it is not more warehousing and logistics, of which there is a disproportionate amount compared to other economic activity. Rather, it needs high value skilled productive employment if it is to reduce the outflow from the district of persons in work, as is the aim of the plan. There has been an empty site on the existing Magna Park for a long time. If it had been available to build an industrial unit it could have been in productive activity by now. A maximum percentage for B1(b) and B1(c) site activity to be permitted would allow for a flexible response to local demand and lessen the tendency to a 'monoculture' of B8.