I was in the middle of writing a post about the chicks' development this afternoon when I received a phone call: "one of the chicks is in our courtyard". We were in the middle of preparing for fledging which I thought would not come until next week so this was taking us a little bit by surprise.
Reviewing the recording, at 14:09, the chick went to the right hand side of the ledge and leapt over the parapet. The courtyard where it was found was on the other side of the ledge so it must have managed some flying. The workers who found it managed to put a box over it and we waited for Dave to come over to check it and release it to the roof.
By the time Dave arrived, we had realised that a second chick had left, in exactly the same way, at 15:31. It has been looked for but not found yet.
Dave got the box off the chick and gave it a good inspection. Verdict: a female, in good condition, but looking like 2/3 days from fledging. Very feisty and very strong, she didn't want to let go of the gloves when Dave put her in the box...
As you can see, feathers fully developed, but still a bit of down at the base of the tail.
We brought her up all the way to the roof, above the nest ledge and quickly left.
She quickly jumped onto that wall on her left and must have followed it around the building as I found her (at least I think it's her) above her parents a while later.
As I am typing this, the third chick is asleep in the nestbox, it must be feeling lonely...