I have found a James Garnham in my 'tree'. He was the son of Samuel Garnham [b. 1793 Hopton by Thetford]and Elizabeth Garnham [born 1796 Botesdale]. James was born in 1818 together with his twin brother William but sadly both died in 1818. So they were not very old.
In 1822 Samuel and Elizabeth had another son who they called James and he lived til 1897 aged 75 years.
A sister to James - Eliza [born about 1816?] married a William Prentice on 9th April 1854 at South Lopham. They produced a son James in 1843 and he died 1877 aged 34.
Don't know if any of the above is relevant to your Garnham family and if not, happy hunting.