Yeah, seen it several times, usually under the WS roof. Only reason it came up during the tour is because I noticed it there then and asked. Don't know a lot about falconry but can't imagine it would be bothered by what's going on on the pitch.
Does it nest in the roof ? When I did the stadium tour the guide said one of the groundstaff was a raptor enthusiast and kept it and took it along to work.......