Okay, this is a bit strange, given that so far everything else seems to fit the information you have previously provided. It shows that Ann was MEAD not GRAY?? I will see if I can sort out what's going on with her...
Until then, it appears that this is them again
1861 Census England Somerset Yeovil
RG9/1644/31/13
Back Street
SHERGOLD
George Head Marr 26 Ag Lab Wiltshire Wilton
Ann Wife Marr 22 Somerset Yeovil
Harry Son Unmarr 4 Scholar Somerset Yeovil
Sarah Dau Unmarr 1 Somerset Yeovil
Sarah MEAD Mother in Law Wid 47 Leather Glover Somerset Yeovil