Never had Macpherson, in his own view, appeared to greater advantage than as acting governor-general of Bengal between the departure of Warren Hastings, with whom he had fallen out, and the arrival of Cornwallis, who had nothing but contempt for the pretensions which had so favourably impressed administration when he bought his way into Parliament in Lord North’s time. (North himself was not surprised that such an assiduous flatterer flattered himself, in parody of Macpherson’s favourite phrase.) He was dismissed the Company service for a second time, or rather bought off, in 1789 when he threatened to return to India, at first by the promise of a pension of £2,000 p.a., but subsequently by the payment of £15,000 arrears of salary for the nominal seat on the council of Bengal which he then relinquished. He also had financial claims on the nawab of the Carnatic which he pressed for the next 20 years.
Overlaying the arts of a soothsayer from the isle of Skye with Asiatic adulation, Macpherson laid siege to the Prince of Wales, to whom he had first been introduced about 1780. Nathaniel Wraxall recalled:
Soon after Sir John Macpherson’s return from Bengal, the Prince of Wales commenced an intimacy with him which lasted ... from 1788 down to 1802, when it became suddenly eclipsed and never revived. During that time few individuals enjoyed more distinguishing marks of his Royal Highness’s favour. Sir John communicated constantly with him by letters while travelling on the Continent. When in London, he was admitted to Carlton House at almost all hours, frequently when the heir apparent was in bed.
During the Regency crisis he brought over his kinsman James Macpherson and Sir Samuel Hannay to the Prince’s side, though without a seat in the House himself. (A project of the Duchess of Gordon to bring him in for Banffshire, without ‘an acre’ there, had been discounted.) In December 1789 he set out on a continental journey of which the aim became ‘to counteract the Revolution’, as he grandly characterized it, for he was a convert of Edmund Burke. His visions, conveyed to the Prince, included the Pilnitz conference of 1791, for which he claimed credit, and a union of England with the German Empire to secure the peace of Europe. He and his secretary Macaulay were dubbed ‘the gentle giant and his pocket pistol’ and he was ‘at all times a busy politician’ and insisted on meeting the potentates. ‘Attentions from such heights’ he wrote, ‘have a powerful effect on every liberal mind.’
Returning to England in 1793, Macpherson was an ‘alarmist’ who sought to win over his former patron’s son the 3rd Earl of Guilford to ‘support the constitution’. He was suspected of intrigue, but it was one of many instances of mere meddling. He consistently advocated union of the parties at home and non-interference in the internal affairs of foreign states, basing this policy on his Indian experience, but as Sylvester Douglas put it: ‘he is, alas, such a flatterer, such a placebo, such an universal and habitual sycophant, that it is difficult to get at his real object or his real sentiments from what he says’. Neither Pitt nor Dundas had any time for him and it was through George Rose that Macpherson forwarded French royalist proposals for pacification from Mallet du Pan in October 1794, hoping that ‘facts and events will satisfy [Pitt] that as I was in some measure connected with the prosperous issue of his administration in the East, so I am not indifferent to its eventual prosperity in the West’.
Macpherson doubtless bought himself into Parliament again in 1796, on Viscountess Irwin’s interest, the better to expound his nostrums. He subscribed £5,000 to the loyalty loan, but to the Prince of Wales he had written, 8 Mar., ‘I wish to remain disconnected with the parties in or out of power in this country’. On 9 Mar. 1797 he joined the ‘armed neutrality’ of Members mustered by his friend Sir John Sinclair. The same day he opposed Pitt’s Bank measures and voted (as also on the 13th) for the inclusion of Fox on select committees. His only known speech in that Parliament, 10 Apr. 1797, was to second Pollen’s motion, which he had declined to move himself, to review the prospects for peace negotiation. He raised a laugh by calling for unanimous support for the motion, which was heavily defeated. On 15 Nov. and 16 Dec. 1797 he wrote two Letters to a noble Earl [Moira], afterwards published, advocating a coalition of Pitt and Fox, the latter to give up parliamentary reform for the time being and the former to impose a ‘general and equal land tax’ and recognize the French directoire as a basis for armistice. His appeals to Pitt and Fox to the same effect were unavailing; but to Sheridan he wrote, 21 June 1798, that opposition’s was the unpopular cause and that war must be continued to re-establish freedom in Europe. Thus he was no longer active in the House, though he claimed to have supported Pitt’s income tax proposals, but a busybody behind the scenes. In October 1799 he was anxious to promote good relations between the King, Pitt and the Prince of Wales and urged continental employment for the latter to restore unanimity among Britain’s allies. He predicted that Buonaparte, as first consul, would bid for peace.
Macpherson, though a ‘retired farmer’, continued to air his views. Canning described him, 16 May 1807, as
a mad politician, the correspondent (so far as that term applies to a man who writes letters, but receives no answers) of all the crowned heads in Europe, and for aught I know in all the other quarters of the globe.
As the Prince of Wales’s Regency approached, he wrote fulsomely to his secretary McMahon of his messianic expectations. Even in his heyday he had been what Lord Malmesbury called ‘an intruding man; perhaps well meaning; more duped than duping’; but even those who did not think him crazy, found him irritating—his compatriot Minto dubbed him ‘the most horrid of all Scotch Scotchmen’. His ‘slow soft drawling manner’ was ‘very tiresome’, claimed Lord Glenbervie, whose wife chimed in: ‘His words come from his lips like drops of laudanum from a vial, and they produce the same effect’. His friend Wraxall gave him credit for the ‘desire of fame and the ambition of meriting it by personal sacrifices and renunciations’ and for being ‘philosophic’, and noted his imposing physique, ‘performing a strathspey at seventy almost like a youth of eighteen’.
Macpherson died 12 Jan. 1821, leaving legacies of £18,500 in Carnatic stock, and a bust of Minerva to King George IV, for whom he expressed his ‘early and unalterable admiration’.