Tried various spellings and found a George COXFORD death in 1897 aged 68. This sort of ties in with his ages in 1851 and 1871.
Might be him. Buried at Karori 23 Aug 1897 aged 71.
Looks to have been baptised at St James Clerkenwell on 15 Aug 1830, born Jun 7, s/o Thomas and Hannah, which fits with 1851 and 1861.
Ian C