Some Iranian historians have criticized him for joining Freemasonry and also for receiving gifts and an annuity from the British (E. Rāʾīn, Ḥoqūthat-begīrān-e Engelīs dar Īrān, Tehran, 1348 Š./1969, pp. 20-43). Receiving gifts was not uncommon among the courtiers of Fatḥ-ʿAlī Shah, but a regular annuity from a foreign government was unusual. James Fraser, who did not think highly of Mīrzā Abu’l-Ḥasan, wrote of him: “Although he has for a long time past, and I believe still receives a considerable annuity from the English government, and has returned to Persia loaded with its presents, he constantly opposes its interests, and talks of it before his countrymen generally in very slighting terms” (J. B. Fraser, Narrative of a Journey into Khorasan in the Years 1821 and 1822, London, 1825, p. 151). Despite Fraser’s statement, most of the sources confirm that Mīrzā Abu’l-Ḥasan was a staunch supporter of the British, and for his good services he was paid an annuity of 1,000 rupees from 1810 to 1845, the year of his death. According to the British Foreign Office documents (F.O. 60/vol. 118), in 1843 Mīrzā Abu’l-Ḥasan asked that after his death his salary should be paid to his son; correspondence (31 January, 13 May , 18 March, and 27 March 1848; cf. Rāʾīn, op. cit., pp. 37-38) indicates that his son pursued the same aim without success.
After his return to Iran, Mīrzā Abu’l-Ḥasan, who received the honorary title of Khan from Fatḥ-ʿAlī Shah, worked closely with the British ambassador, who played an important part in drafting the Treaty of Golestān. Sir Gore Ouseley—who had included Mīrzā Šafīʿ (q.v.), the prime minister, in the British payroll (F.O. 60/7 1812, letter no. 16)—enlisted the services of these two officials and outmanoeuvered Mīrzā Bozorg Qāʾem-maqām (q.v.), the patriotic minister to ʿAbbās Mīrzā, who opposed this ignominious treaty. Ouseley’s main concern was to safeguard the British and Russian interests and enable the Russians to face the Napoleonic army without being disturbed by Iran. On behalf of Iran, Mīrzā Abu’l-Ḥasan signed the treaty in the village of Golestān in March, 1813.
The Golestān treaty enacted a ceasefire but left the fate of the Iranian territories occupied by the Russians to be resolved later. In 1815 Mīrzā Abu’l-Ḥasan was sent to the court of St. Petersburg as special envoy; though Sir Gore Ouseley had promised Fatḥ-ʿAlī Shah to negotiate for the return of the Iranian territories with the czar, nothing came out of this trip, and Mīrzā Abu’l-Ḥasan returned to Tehran after two years. In 1819 he was again sent to England, traveling overland via Constantinople, Vienna, and Paris, and he returned in the following year. In 1239/1823 he was appointed minister of foreign affairs, the second foreign minister of Iran after Mīrzā ʿAbd-al-Wahhāb Moʿtamad-al-dawla Našāṭ (q.v.). Until 1250/1834, when Fatḥ-ʿAlī Shah died, Mīrzā Abu’l-Ḥasan held this position and was involved in most Iranian major foreign policy decisions. He and Našāṭ were among the very few officials who opposed the policy of war with Russia, but they could not cope with the wave of militancy which was being fanned by some of the ʿolamāʾ. When Iran was again defeated in her struggles against Russia, Mīrzā Abu’l-Ḥasan and ʿAbbās Mīrzā, the crown prince, signed the Treaty of Torkamāṇčāy (q.v.) on 5 Šaʿbān 1243/28 February 1828.