Alsthom and Germany's Krauss Maffei. The inclusion of foreign manufacturers was in part due to the limited domestic experience with trainsets capable of such high top speeds. A total of three companies, ASEA, Brush Traction and GEC, submitted tenders for the design and construction of the Class 91 locomotive. On 14 February 1985, the BR board approved the substitution of the Class 91 for Class 89 for the ECML programme. The tendering process was relatively complex, but a decisive move appeared to have been GEC's offer of a sub-contracting arrangement to BREL for the construction of the locomotive's mechanical elements. It would be GEC's submission that would be selected as the winner; after which a contract for the construction of 31 Class 91 locomotives, along with an option for 25 more for the WCML, was awarded during February 1986. Shortly thereafter, BREL established a production line for the type at its Crewe Works. Post-introduction developments The first passenger service to be operated by a Class 91 locomotive was the 17:36 King's Cross to Peterborough on 3 March 1989. From 6 March, members of the fleet began to work services between London and Grantham, and from 11 March services between London and Leeds. With the completion of the East Coast Main Line electrification programme, Class 91 trains reached Newcastle upon Tyne for the first time in service on 10 June 1991, then Edinburgh on 12 June. In service, as a part of the InterCity 225 sets, the fleet worked alongside locomotives and electric multiple units. Diesel trains displaced by the Class 91 introduction were reallocated predominantly to the Midland Main Line. The InterCity 225's introduction correlated with a significant increase in passenger numbers using the ECML within two years; one station recorded a 58 per cent increase in passengers. In the early 1990s, after the cancellation of InterCity 250, British Rail examined the option of ordering a further set of ten Class 91s to operate on the West Coast Main Line with UK Treasury support, however the business case for these failed to prove sufficiently worthwhile. and led to the electric Networker Classes 365, 465 and 466 EMU Networker stock's procurement being taken forward. The locomotive body is asymmetric; streamlined at the 'front' (Number 1) end , but left 'blunt' at the Number 2 end so as to visually blend with the fixed sets of Mark 4 coaches in normal push-pull