Rutan16,
Don't think it would be Liege originating steel, its only a short drive from Liege area to Nottingham, I can do it by car including Eurotunnel in nine hours, a truck would obviously take a little longer (when I worked in logistics our drivers could do Birmingham / Aachen in 12 hours and that using the ferries) but still I can't see a significant benefit in flying as opposed to trucking from that area provided there are no issues with the train, ferries or customs. Moreover the steel works at Herstal, about 20 minutes from Liege Airport is largely derelict now, not sure if it is still in production. Of course it could originate from further away.
N707ZS
BHX runway is actually slightly longer, by a few metres, than EMA and quite often, if not regularly handles 747 freighters already.
I reckon crew change might be the most likely.