Nigel is the affectionate (?) name given to a BA pilot.
It is out-dated now as it refers to the old image of BA pilots all being from the old boy network.
Having thought about it, it may be an affectionate nod at BA pilots, but it could be used by some who are jealous of those flying for the flag carrier (or not as the case is with some of the BA fleet curently!)
FJW.