An unusual noise on top of the tower drew us outside to check and there the male stood squawking wildly in protective mode as the female chased an intruding peregrine around the tower and up to higher altitudes in ever increasing circles. This went on for about 5 minutes before the intruder was hopefully chased away and the male returned to the nest, while the female went off into the sunny north-west, no doubt on another hunting trip. Everyone seems happy and safe again and the nest is quiet. We couldn’t identify the intruder at all (sky too bright) but it wasn’t welcome. First thoughts were that it was the younger peregrine from earlier this year on a return visit.