However, BREL's Doncaster Works were in severe demand at this time and its resources would be stretched to meet these targets despite the ample fabrication facilities available on site, as a lack of numbers of skilled personnel to manufacture mechanical components was the primary limitation on capacity at Doncaster. To address this constraint, Ashford, Eastleigh and Swindon Works were also involved in the fabrication of sub-assemblies to successfully satisfy the production timetable; specically, roofs, fuel tanks and cab frames were produced at Ashford, while cab desks were built at Eastleigh, and radiator housings were supplied from Swindon. Subsiquently, final assembly of the type was transferred from Doncaster Works to Crewe, allowing the latter to commence work on construction of the new Class 58 heavy freight locomitive.