Could this be your William
1871 - RG10/668/31/13
4 Cross Street, Lambeth
George SMITH, head mar 44, Bricklayer unempl., born Surrey, Lambeth
Elizabeth SMITH, wife mar 43, born ditto
William SMITH, son unm 23, Carman unempl., born ditto
They were at the same address in 1861
1861 - RG9/343/66/42
14 East St, St Peter Walworth
George HAWTIN, head mar 47, Smith & Iron Plate Worker, born Surrey, Newington
Mary Ann HAWTIN, wife mar 41, born ditto
George HAWTIN, son unm 21, Carman, born ditto
Hannah HAWTIN, dau 14, Scholar, born ditto
Emily HAWTIN, dau 11, Scholar, born ditto
Georgina HAWTIN, dau 6, born ditto
Alfred HAWTIN, son 5mo, born ditto
Whereabouts in NZ did they come to?
Ian C