Green’s Dictionary of Slang

foolish, weak-minded; thus culver-head n., a fool, a simpleton.

1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
a.1909		press cutting in J. Ware Passing Eng. of the Victorian Era 101/1: When the culver-headed yeknods are down in the dumps, strike us pink if they’re not as humble as a blackberry swagger.
1909		J. Ware Passing Eng. of the Victorian Era 100/2: Culver-head (Lower Classes). A fool; practically calf-head.