Church was set up in business in London by his wealthy uncle, John Barker of Mansel Street, a director of the London Assurance Company. According to a defamatory account of his career published in 1794, Stock Exchange speculation and gambling were responsible for his bankruptcy in August 1774, when he was described as a grocer, with premises in Mark Lane.
In Boston, Church embarked on a variety of business ventures, including banking and shipping, and speculated in currency and land. He and his business partner, Colonel Jeremiah Wadsworth of Hartford, Connecticut, secured a contract for provisioning the French forces in America in 1780, and two years later they were contracted as sole suppliers to the American army as well. Church prospered, and James McHenry, Washington’s former secretary, noted in 1782 that he had ‘riches enough, with common management, to make the longest life very comfortable’.
He went with Wadsworth to Paris in the summer of 1783 to settle his accounts with the French government and for the next two years travelled between Paris, where he became friendly with Talleyrand and renewed his acquaintance with Lafayette, and London, where he secured his discharge from bankruptcy in November 1783 and purchased a town house in Sackville Street. He returned briefly to America in 1785 to wind up some of his business affairs and dissolve his partnership with Wadsworth, and entrusted the management of his remaining interests in bank stock and land to Hamilton. In 1786 he bought a villa near Windsor. The Churches lived in extravagant style and their doors were always open to distinguished American visitors. A dedicated and skilful gambler, he became friendly with the Prince of Wales and Fox, to whom he lent at least £9,000.
Church, who was ‘recommended to the Whig party’ by John Sawbridge, contested the vacant seat at Maldon in February 1787, not with any hope of immediate success, but ‘in order to spend a few hundreds to prepare his way for the general election’. He joined the Whig Club in April and considered standing at the Windsor by-election in June 1787, when George III remarked that ‘his principles are so avowedly enemical [sic] that his political conduct may easily be judged’. His wife told Hamilton, 2 Oct. 1787, that his ‘head is full of politics, he is so desirous of making once [sic] in the British House of Commons’; and the following year he bought the Verney property at Wendover, for which he returned himself at the 1790 general election.
In the House, Church, who privately condemned Pitt as ‘a very great rascal’, sided with his Whig gambling cronies. He was involved, with the French ambassador, in some unsuccessful stock speculation during the Nootka Sound crisis, and on 3 Nov. 1790 he wrote to Hamilton that ‘a mad credulity prevails here just as it did at the commencement of the American war, we despise our enemy, and dream of nought but victory’.
He returned with his family to New York the following year. When Robert Morris went bankrupt, Church, who had lent him large sums, took over the security, 100,000 acres of undeveloped land in western New York state, and gave a half-interest to his eldest son Philip, who developed it and founded the town of Angelica. He continued to engage in speculative enterprises, but lost heavily in buying up spoliation claims against the French government and eventually his share of the western lands was sold for the benefit of his creditors. In 1799 he fought a duel with Aaron Burr, the future vice-president, and ironically it was with Church’s pistols that Burr and Hamilton fought their duel, in which the latter died, in 1804. At least £2,500 of Fox’s debt to Church remained unpaid by 1806, and he made a number of attempts to recover it both before and after Fox’s death. Lord Robert Spencer admitted that his claim was strong, but it became clear that it could not be met directly in cash and Church instructed his son, who was in England in 1811 and 1812, to try to secure a compensatory ‘provision’ through William Adam’s influence with the Regent. When Philip Church returned to America in October 1812 it was ‘without taking any steps respecting’ his father’s claim, although he did not feel justified in ‘formally abandoning it’, and he thanked Adam for his efforts to promote an unspecified ‘object’, which he considered ‘as fully obtained as the circumstances of the time will permit’.
Church returned to England about 1814, after the death of his wife, but was evidently unable any longer to cut a figure in society. He was buried at St. James’s, Piccadilly, 2 May 1818, and his effects were assessed at a modest £1,500.