There is a John Caine Srevant unmarried 21 Carter b Marown in the 1861 cenus in German. He is with the family of William and Mary Jane Caine ar Skirsdale Veg? German RG9/4420 folio 58 page 6.
The only Ann Cain(e) that I found aged 18-20 was Ann servant Ourysdale Michael with the family of William and Margaret Quiggan RG9/4431 folio 7 page 7.
However, she is shown as being born in German.
As I found no German born Ann Caine of the appropriare age in 1851, this could be she.