When we planned the current parallel taxiway (Alpha) we did look at going to the end but it would have taken a tremendous amount of infill – somebody did work out how much and we would have needed virtually every dumper truck in southern UK – and it was just ‘too difficult’. Plus the airport didn’t (doesn’t ?) own the land to keep the taxiway truly parallel and it would have had to cut in closer to the runway. OK for CAT I ops but the CAT II/III holds would have ended up where they are now. So for expedition we plugged the taxiway in where it is now. We did consult the airlines and their view was if you cannot go to the end don’t plug it in too close because steering geometry issues. All this was a long time ago.