His father, at one time assistant-secretary of the Bank of Scotland, was engaged in business at Glasgow; his mother, Juliet Parish, was the daughter of a Hamburg merchant of Scottish extraction.
On the cession of the city to the Banda Oriental, he was sent home by his father, but in 1808 sailed on his own account for Rio de Janeiro, where he was employed as a clerk for three years.
At the end of 1811 he went as a mercantile agent to Asunción, but in 1815 was compelled by the dictator José Gaspar Rodríguez de Francia to leave the country, along with his younger brother, William Parish Robertson, who had joined him.
Sailing for Buenos Ayres in 1820, he commenced trading with Chile and Peru, and landed at Greenock in 1824 or 1825, with a fortune of £100,000, as the representative of some of the South American republics.
[2] Intending to devote himself to study, Robertson entered Corpus Christi College, Cambridge;[3] but in 1833 he moved to the Isle of Wight for his health.