It's certainly Griselda in the DT version, the Steeleye Span one which is, I think, based on the one Bert Lloyd used to sing; though it renders "Arthur Marvel was the man who brought the Skewball over" as "Oh the marvel was the man..."! Surely the point is that Skewball was an English horse, brought over to race the native Irish champion, the grey Griselda, on whom the local sportsmen 'laid their purses'.

It also sounds on the record as if they are singing "Sporting plains of Kielder" [Tim Hart mentioned this ambiguity in his notes], though of course it is Kildare, where the Curragh racecourse is situated. Kielder is a place in the Lake District, site of a famous reservoir, and formerly home of a well-known hunt iirc.

~M~