As a child Fullarton succeeded to great estates and the headship of a family with extensive East Indian connexions. He was brought up in Edinburgh with William Adam, and after the Grand Tour he began to read for the bar. But at the age of 21 he was appointed principal secretary to Lord Stormont, then ambassador in Paris, by whose interest with North he was brought in for Plympton.
Described by the Public Ledger in 1779 as ‘a hungry Scotchman ... willing to do anything he is—[paid] to do’, Fullarton consistently supported Administration. When William Adam fought his duel with Fox in November 1779 he borrowed Fullarton’s pistols,
Fullarton did not seek re-election in 1780. The Cabinet having finally approved the South Sea expedition in August, Fullarton and Humberston were authorized to double the size of their regiments; but on the outbreak of the Dutch war the force was diverted, first to the Cape of Good Hope and eventually to India.
Having maintained his attachment to North, Stormont, Adam, and other Opposition leaders, Fullarton became connected with the Prince of Wales; and when in 1787 his friend Francis Charteris was obliged to vacate Haddington Burghs, Fullarton succeeded him as an Opposition candidate.
An able debater, he spoke with authority on Indian affairs, and opposed the declaratory bill on 5 Mar. 1788 as unfair to East India Company officers. On 9 May he ‘inveighed against Impey as a criminal of the most atrocious description whose ermine was steeped in human blood’. He was an equally effective Opposition speaker in the Regency debate of 16 Jan. 1789. An uncompromising critic of Hastings, in the debate of 15 Mar. 1790 on the execution of Mustapha Khan he maintained that no British officer was obliged to obey a cruel, illegal order.
He lost his seat in 1790. He died 13 Feb. 1808.
