Vansittart was promoted to the grade of factor, and in the following year visited England. He had amassed a considerable fortune, which he soon dissipated in gambling and riotous living. With his elder brothers, Arthur and Robert, he was a member of the graceless Society of the Franciscans of Medmenham. Returning to India, he was employed in 1754 and 1755 in embassies to the French East India Company, and for his services was promoted to the rank of junior merchant. In 1756 he was advanced to that of senior merchant, while acting as secretary and Persian translator to the secret committee. In 1757 he took his seat in the council, and was appointed searcher of the sea-gate. In February 1759 he took part in the defence of Madras against the French under Lally.
On 8 Nov. 1759, on Clive's recommendation, he was appointed president of the council and governor of Fort William and the company's settlements in Bengal, Behar, and Orissa; but owing to the critical condition of affairs at Fort St. George, where he was acting as governor ad interim, he did not arrive in Bengal until July 1760. His promotion occasioned much discontent at Fort William, due, in part at least, to the fact that he was junior to any member of the council there, and a petition was drawn up by John Zephaniah Holwell [q. v.], the temporary governor, on 29 Dec. 1759, which was signed by the members of the council, remonstrating against his appointment. The directors, however, upheld Vansittart, and in a reply, dated 21 Jan. 1761, removed the petitioners from their official places.
Vansittart arrived in Bengal at the end of July 1760. He found affairs embarrassed. Clive, by undertaking to assist the subadar in military matters, had entirely changed the position of the company in Bengal. By the treaty with the subadar, Mír Jafar, the company undertook to maintain a force under their own direction, but in the subadar's pay, to be at his service when he should require it. The sum for its maintenance was afterwards fixed at a lakh of rupees a month. The new governor found this subsidy unpaid, the treasury empty, and the income of the presidency scarcely sufficient for the current expenses of Calcutta. Nothing was to be expected from Mír Jafar, who was alienated from the English, and who besides had entirely lost control of the administration. The death of his son Mirán on 2 July 1760 plunged matters into inextricable confusion by removing the only man able to control the subadar's troops. Under these circumstances Vansittart resolved to place the administration in the hands of Mír Kásim, Mír Jafar's son-in-law, a man of undoubted ability and well affected to the English. On 2 Oct. 1760 Vansittart proceeded to Kásimbázár, and, finding Mír Jafar resolutely opposed to his plan, deposed him, and at his own request sent him to Calcutta. His successor, Mír Kásim, by a treaty previously concluded on 17 Sept., assigned the revenues of the provinces of Bárdwán, Midnapur, and Chittagong for the maintenance of the company's troops, and placed them under English administration.
In April 1761 a serious difference arose between the English military and civil authorities. Mír Kásim, on assuming authority, among others, summoned Ramnarain, the financial official of Patna and a protégé of the English, to give in a statement of his accounts. This, however, Ramnarain, supported by the military officers at Patna, Lieutenant-colonel (Sir) Eyre Coote (1726–1783) [q. v.] and Major John Carnac [q. v.], steadily evaded doing. Vansittart at first was fully disposed to protect Ramnarain, and sent directions to Patna that if he made a statement of his accounts he was to be sheltered from attempts at extortion. Ramnarain, however, persistently evaded Mír Kásim's demand, and, relying on the connivance of the English, aspired to independence. He coined money in his own name, and Carnac, under pretence of protecting him, publicly, with an armed force, menaced and insulted Mír Kásim. Consequently Vansittart and the council recalled the two officers, leaving Ramnarain at the discretion of Mír Kásim, by whom he was imprisoned and afterwards put to death.
Though harmony was thus established for the moment, the state of affairs in Bengal was such that fresh disputes were inevitable. The company's servants were at that time allowed to engage in private trade, and the result was unfathomable corruption. By unjustifiably extending the privilege of trading free of duty to cover internal as well as foreign trade, by granting ‘dustucks’ or passports for their own and their servants' goods, as well as for those of the company, and by insisting that their native agents should be totally exempted from the subadar's jurisdiction, the English officials had engrossed the entire business of the country, and had established an independent government by the side of the nabob's. Vansittart set his face against these abuses, but the authority of the president was extremely limited. He was little more than chairman of the council, which determined all administrative action by a bare majority. He had hardly begun to take remedial measures when a peremptory order from the directors dismissed from their service three members of
