During my time 'holding' at HQCC Northwood in 68-69, I had to visit Northolt on a number of occasions. On one visit I remember being taken out on to dispersal (no yellow jackets or people shouting at you if you didn't have one) to see some of the visitors. one of which was an Indian Connie which had arrived earlier that day. My guide (a fellow 'holdee') took great delight in pointing out a large birds nest happily and obviously securely built into one of the rudder hinges. Apparently it had been pointed out to the crew on their previous visit some weeks before, but they had replied that it was 'unlucky' to remove it!