You can try to pass the buck as much as you like but the responsibility for this incident rests squarely on the captain and co-pilot. In this case it was unlatched cowlings but it could just as easily been something else. The incident was the result of a poor walkaround.
I question the logic of flying the track below instead of diverting over less densely populated area to Stansted.
I see that ground crew are facing the blame.
It is now believed two engineers, one of them a supervisor, have been suspended while an investigation is carried out.