Hello Graham and all
You may want to look at the actual 1851 image yourself; it doesn't say that the Susanna listed is William's grand-daughter, it says William is still married and Susanna is his wife, born Hastings! The age could be 10 or 70. I suppose it is possible that the census taker combined two lines when transferring the information from the original census papers (which were all destroyed), or that this is all that were in the household.
If you PM me (there's a button in this reply that says something like "send this person a personal message" with your e-mail address then I can send you the image; we can't do it directly through Rootschat. DON'T put your e-mail address on this board!
Kind regards
Gaie
No, got that wrong, it's the green scroll thing to the left of the posting