Roud lists it at no. 8092; all but one example at present (The Fremington Great Meat Pie, a localised Devon variant recorded from Phoebe Birch in the mid 1970s) are 19th century broadside editions. Some can be seen at  Bodleian Library Broadside Ballads:

The great meat pie

Peter Kennedy got a set from Tom Brown of Yarmouth in 1979. During the 1960s and early '70s, though, the song as posted by Joe above had considerable currency around the folk clubs and on those radio programmes that played such things; and on childrens' television, I think (I'm pretty sure I remember Wally Whyton singing it, along with songs like the Derby Ram, accompanied by cute but simple animations). An edited and re-made version of the broadside song, it seems, and set, so far as I can remember, to a fairly well-known American tune that I can't quite seem to pin down at the moment.

Giant Meat Pies were a real issue at one time, and quite a focus of community pride. They were only produced for very special occasions, though, and preparation wasn't always all it might have been. I read once about one case where the filling went off before it could be properly cooked; it apparently took almost as much trouble to dispose of the wreckage as it would a beached whale.