The Gentleman’s Magazine wrote in his obituary (1785, p. 570):
Mr. Atkinson when he came from the North was a mere adventurer, unsustained by any inheritance, by few family friends of any power, and by no acquisitions which education imparts but common penmanship and arithmetic. Thus circumstanced he came to London, and passing through different counting houses and experiments in trade, accumulated that prodigious wealth of which he died possessed, and which he had long enjoyed.
In 1774 he was a partner in the firm of Mure, Son, and Atkinson, of Nicholas Lane (and later of Fenchurch St.), West India merchants. During the American war he held a number of large government contracts for the supply of rum, victuals, and other necessities to the troops in North America and Gilbraltar.
In 1783 Atkinson took the lead in the Company against Fox’s East India bill; and in 1784, seeking more power, pressed for reforms more drastic than Pitt and Dundas judged acceptable. At the general election he stood unsuccessfully for London as a supporter of Pitt; but two months later, at Pitt’s request, was returned by Sir Edward Dering for New Romney, ‘though much against Sir Edward’s inclination, as not liking Mr. Atkinson’s character’.
Atkinson died 28 May 1785, said to be worth over £300,000.