In the 1901 book Highways and Byways of East Anglia, Black Shuck is accorded this bloodcurdling description.
"He takes the form of a huge black dog, and prowls along dark lanes and lonesome field footpaths, where, although his howling makes the hearer's blood run cold, his footfalls make no sound. You may know him at once, should you see him, by his fiery eye; he has but one, and that, like the Cyclops', is in the middle of his head. But such an encounter might bring you the worst of luck: it is even said that to meet him is to be warned that your death will occur before the end of the year. So you will do well to shut your eyes if you hear him howling shut them even if you are uncertain whether it is the dog fiend or the voice of the wind you hear. Should you never set eyes on our Norfolk Snarleyow you may perhaps doubt his existence, and, like other learned folks, tell us that his story is nothing but the old Scandinavian myth of the black hound of Odin, brought to us by the Vikings who long ago settled down on the Norfolk coast"
Whether such a demonic creature can be reconciled with anything of flesh and blood is doubtful, but Shuck has been haunting the drear marshlands of the fens for centuries - possibly making his debut in the Peterborough Chronicle of 1127, where he is described in the company of black huntsmen on huge black horses.