Brilliant, thanks Trish. CaroleW & Bearcat. The Mary Ann Hawkes marriage fits perfectly. Kate Mills, nee Hawkes is her auntie. It is interesting that the marriage register has her father, John Hawkes a labourer, as deceased in 1882. Mary Ann’s mother died in 1867 and the last I had on her father was in 1868 (a newspaper reference to him). So now I know that John Hawkes, born 1835, died between 1868 and 1882.
Harriet is still probably a loose end. I have found a marriage between Harriet Hawkes Robbins, widow, aged 39, on 3 January 1898 in Manhattan, New York. Her parents were recorded as Wm Hawkes and Ann Pollak. So the Robbins linkage is not to our Harriet Hawkes.
The other loose end is their sister Ann Hawkes, born 1858. She was a general servant, aged 14 in the 1871 census. I have not found anything about her since the 1871 census. I initially thought she married Henry George Shorter in 1880 but the 1881 census has that Ann Shorter, nee Hawkes as born in Brabourne, Kent (not Snodland). So not the one. Ann and Harriet were close in age so they may have gone somewhere together.