Looking for Newman IN Sanford Springvale Maine and IN New Hampshire 1800 S 1900 S

Robert James NEWMAN, born 1836 in 'England' and we believe London. His father, also Robert of London, served at Waterloo as a tailor with the Coldstream Guards. At some point the 'family' left England and Arrived in America. Robert James was placed under the guardianship of one Benjamin Newman (possibly of England and/or New Hampshire and possibly a much older brother) in 1846 through the Court in Sanford, Maine. Benjamin, his wife Betsy, and children - including Robert James - appear in the 1850 census of Sanford Maine. In 1854, aged 18, Robert James sailed away to Australia on the Barque 'Homer' landing there in July 1854. Since then, to the present day, we have a huge file on him but have never been able to prove his birth.,
Please, can anyone help.