But this is, in fact, a gurnet, which is a kind of fish.
It really does look menacing on that plate, though. And the shadow/plate design just under the head looks like a big jaw with long teeth.
Philip Harben was a British cooking authority of the 1940s and 1950s. He wrote a cooking column for Women’s Own magazine, and wrote many cookbooks. He also had the first TV cooking show ever, in 1946, on the BBC. It was called Cookery. (And that is about as many times as I want to use words beginning with c-o-o-k in one paragraph!)
And gurnet or gurnard is a rather cheap, inexpensive and bony fish. Apparently Mrs. Beeton had a recipe for it, see here. It does look bony, doesn’t it? And like it’s ready for a good meal itself, as opposed to vice versa.