I spotted a crow with a grey back at Minsmere today. It flew past Bittern Hide at about 2.10 pm, but I was wathcing from near the sluice - about half a mile away. It didn't seem to have enough grey to be a hooded crow - and the grey seemed too dark. I think it was a hybrid between carrion crow and hooded crow. Although rare, there have been a couple on the coast in recent months. Hooded crows are very rare migrants on the East Anglian coast, so the hybrid is perhaps more likely.
Did you see it? If so, what were your thoughts. If you were in Bittern Hide at that time you shoudl have had a good view.