Tricky. There's a Thomas and Sarah Hussey in Burnham, where John claims to have been born, but they're a wee bit too old to be having children in 1856
I suspect this is your man
John Hussey Miles
Birth 14 Feb 1856
Baptism 15 Mar 1857, Burnham
Mother: Ann Miles
1871!
Thomas Hussey 71
John Miles 14 Stepson
William Miles 16 Stepson