Doh - she's on the 1871 - a year older than Mary ..... never noticed as we didnt transcribe that entry ...
What are you saying about the problem with Ann/Mary Whetton??
Here they are in 1881:http://search.ancestry.co.uk/cgi-bin/sse.dll?db=uki1881&indiv=try&h=12220525
OK so I now have Mary living with her Mother in law and new husband in 1881. That is cool.