I was in Derby yesterday and had a bit of time to spare so I went to have a look at the cathedral and one of the birds was flying around at the time and as I walked around the side (amen alley) where you can get a good view of the scrape platform and was not disappointed, one was on the edge of the platform and another was on the stonework.
I watched for about 20 mins. and spoke and spoke to a number of people who use the alley each day but had no idea that the birds where there

and thanked me very much for pointing them out

.
I think I will contact Derbyshire Wildlife Trust and Derby Cathedral and ask them to put some details on a plaque about the birds.