On the 1881 census Ann a Widow is living at Railway Lodge, Castle Church, Stafford, working as a Matron/Servant, her four children are with her. William is 13 years old, and his Mother is only 29 years old, so I think her age must be incorrect on the census and she must have been 34 years old if the other dates are correct, being only 17 when she married Joseph.
Regards.