Years back Qualitair were going to build a 3 bay 747-400 Maintenance facility at BHX just behind where the old hangar 3 used to be.I remember getting a copy of the initial planning application from Solihull Council.
Airlines mooted to want to use it included Korean, Qantas, Singapore.Sadly though noone wanted to actually pay for it and it was scrapped.
Apart from the Eurojet facility, don't forget BHX has to build an airliner engine test facility, either a hangar or open structure with high sides.This was planned to go close to where the ground radar is positioned now..not sure if that is still the case.
This structure was one of the conditions from Solihull Council before they would approved the runway extension.
Nigel