Gulston’s father ‘never was in England’; he himself was head of a mercantile house at Lisbon, presumably inherited from his father.
With Poole, where Gulston established an enduring parliamentary interest, he was probably connected through his extensive trade with both North and South America. In Parliament he regularly adhered to the Government, from whom he held contracts during the war of the Austrian succession, and when war re-started in 1755 Gulston felt indignant at not being immediately re-employed as a money remitter. He wrote to James West, 6 Nov. 1755, that some time ago he had spoken about it to the Duke of Newcastle, who seemed surprised at his early application; but next Gulston ‘found others employed therein’; ‘I am turned out of my post (if I may so call it) without having done anything to deserve it ... I have a sort of right to be employed again and indeed upon an equal footing with any body else the most favoured, which I expect, perhaps more out of a point of honour than profit.’ The Duke had directed him to West, and he now asked for ‘an explicit answer from the Duke, for if it be in the negative, I shall not trouble his Grace any more, which next to granting my request is the greatest favour he can do me’.
In his elections at Poole, a difficult constituency, he had Government support, which was important both because of a group of placemen who could turn the balance between competing candidates, and also because of the favours which a mercantile community with extensive trading interests had to solicit from the Government. There are hints in letters from Sir Peter Thompson, a leading Poole merchant, to James West
Gulston was indeed a sick man, and died on 16 Aug. 1766. According to his daughter, ‘he left in the funds £250,000 ...; an estate in Hertfordshire of £1500 a year; Ealing-grove, and the house in Soho-square’.
