A little bird whispers in my ear that congratulations are due to Shadow Transport Secretary Theresa Villiers. It was apparently her idea for David Cameron to ask Gordon Brown whether he would encourage BA workers to break a picket line and keep the airline flying. The question caused him - as well as the Labour benches - great discomfort. She doesn't normally attend PMQs prep with David Cameron, but after today she might well get a repeat invitation.
A job well done.