Hi there,
I'm sure this is a very weak request (weak as in there must be millions of James Browns!) My 3rd Great-Grandfather, James Brown, came to New Zealand in 1848.  In a book written at the time he is described as 'a Veteran of the Napoleonic Wars'.  His date of birth seems to be fairly flexible.  But I have since found that census dobs can be rounded up or down.  He was born in 1792 in East Crofts, Abbey (Paisley), Renfrew, Scotland.  According to the 1841 census notes I have this is his family:
Address: East Croft St, Paisley, Renfrewshire
James Brown, m, 49, hand loom weaver, Renfrewshire
Marrion ",         f, 40, -, outside county
James ",          m, 13, -, Renfrewshire
John ",             m, 8, -, Renfrewshire
Robt Watt ",     m, 6, -, Renfrewshire
David ",            m, 1, -, Renfrewshire
Do you have any clues as to whether he was at Waterloo?  Or where I should look for Napoleonic War Veterans?  I am in New Zealand and fairly new at this! 
