You can't compare flying to Dubai against Delhi.. 7hrs to Dubai and 9 hours to Delhi !! = more fuel required = more runway length
It's not that simple Nigel, it's unlikely the India flight would be stacked with cargo for instance. Where did you get the 9000 ft value for the B787 btw. Can you link please? That sounds rather extreme.
Consider :
Travel Distance Calculator and Map between World Cities
BHX-ATQ 3983.15 miles
BHX-DEL 4230.80 miles
247 miles isn't the difference between a non-ER B777-200 which used to fly the former route and a B787 needing 9000 ft for the latter.