I spotted the nest not the most tidy (in fact it resembles the Hanging Gardens of Babylon), in a ventilation duct when I was investigating why a bird was being so noisy.
You can just about spot two mouths ready to accept any offerings. There may be others but I don't want to disturb anyone.
This is the mother, rather shy.
And this is the father, rather grumpy. He keeps saying tck, tck, tck.
I believe they are black redstarts but I am happy to be corrected if anyone knows better. Unfortunately they refused to pose for good portraits.
We won't be able to leave the nest where it is, but of course we'll wait until the babies have flown before we do anything.