Blacksheep is right about the Hatfield economy but IMO we were actually the victim of the post-privatisation use of a property company to manage the "real estate" and some strange site cost/output analysis which only recognised complete aeroplanes as output.
The former saw better housing development potential at Hatfield than at (say) Woodford and the latter included the costs of the 125 design staff, airbus subassembly construction, 146 design and subassembly construction and so forth but only counted those 146s finally assembled at Hatfield as output.
The end was in 1993 some 16 years post-nationalisation.