Couple of ideas
According to the 1881 census she was possibly Emily Agnes. The census transcription is a bit of a mess and the actual image isn't much better, There does appear to be an Emily Agnes and an Agnes at the same address, but the both are around 30 and both are spinners. The Emily Agnes is directly under George in the list. There are three other people between Rose and Agnes who is last. Both show Hull as place of birth. Now this could just be a big mix up or it could mean that Emily Agnes (b1878). is somewhere else. It doesn't help much, I know.
The other thing I find strange is that you cannot find the marriage and I cannot find Agnes (snr) birth either - do you have the cert? or just a baptism record.
Only real possibilities I can think of are
that her father died before 1861 and mother remarried and she is ennumerated under that name.
That she was possibly married before.
Also with all the variations of Maguire it is hard to search
How do you know Ann Maguire was previously Kelly?
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