On my way back I decided to have another quick look on the off chance that one of the birds might have gone hunting whilst I was away, hopefully to return with some prey. Nope, both adults were still in exactly the same place! However, about 15 minutes later I saw what I first thought was one of them in the air, so out came the camera. As I was taking shots I scanned the area and saw that the two adult Peregrines were still in the same place and so this was a third bird.
At first I thought it was another Peregrine, perhaps one of last year's young, but when I looked at my photos I saw the streaked breast and tell-tale red 'trousers' of a Hobby! I fully expected one of the Peregrines to see the Hobby off as it circled the nest area a couple of times before flying off. No calls, no movement, nothing - they didn't seem at all bothered.