Hi esterby,
I've been tracking this family back. 1861 (RG9 2628/93 Page 29, 11 Tarvin Common):
William ASTBURY, Head, Mar, 50?, Ag Lab born Cheshire Tarvin
Jane ASTBURY, Wife, Mar, 50, born Cheshire Newchurch
George ASTBURY, Son, Unm, 27, Ag Lab born Cheshire Tarvin
William ASTBURY, Son, Mar, 18, Ag Lab born Cheshire Tarvin
Job ASTBURY, Son, 12, Scholar born Cheshire Tarvin
Joseph ASTBURY, Son, 8, Scholar born Cheshire Tarvin
George ASTBURY, gr son, 4, Scholar born Cheshire Tarvin
I don't see that any of the other children at home are likely candidates for parent(s) of George. (4) William is only 18, and although married, would only have been 14 when George was born. And George (27) isn't married so George (4) wouldn't have his surname.
Isn't it more likely that George put William (grandfather) down as father on his marriage certificate because he may have been illegitimate and had been brought up by his grandparents?
Jean