Nice one and thank you. It went northbound at 5.15pm after circling for 15 mins. Deffo looked like a Nimrod due to the wing thingies. It must have turned left westbound shortly after passing directly over the city centre at 3000ft, or gone up to Upton.
Nice one but would love to know why it was in the "random hold" nowhere near a VOR or NDB. Do you think it came from Waddington?