He did not, however, endorse the extremes of opposition of the colonists. In November 1774 he called on Benjamin Franklin, in London, to discuss the worsening tensions in the cross-Atlantic relationship. Franklin, with Barclay and John Fothergill, drafted a plan to resolve the impasse existing after the Boston Tea Party of the previous year. Barclay met Lord North in 1775 to oppose moves against American access to fisheries, though without success, while Fothergill also worked behind the scenes. After the War, American Quaker abolitionist delegations made their way to London. Barclay found them generally too impatient, and politically naive in their view that the way to apply pressure to Parliament was through the King. He diverted the abolitionist programme to getting the case for the abolition of slavery heard by politicians, with success. In 1781 a consortium of Barclay and others bought the Anchor Brewery, Southwark, part of the estate of Henry Thrale. Barclay approached his widow Hester Thrale the month after his death, with a proposal to acquire a share in the business; this was much more welcome to her than the offer the chief clerk, John Perkins. The deal, requiring some financial engineering, was a family affair involving his nephews: Robert Barclay (1750–1830, of Bury Hill near Dorking, Surrey), son of Barclay's half-brother Alexander, and Silvanus Bevan, to whom Perkins was connected through his wife. David Barclay found £135,000 for the firm. Henry Perkins, son of John, was more of a scholar, but retained an interest in the brewery. The name "H. Thrale and Company" was changed to "Barclay Perkins and Company", in 1798; that company merged with Courage Brewery in 1955. Barclay bought the manor of Youngsbury in Hertfordshire in 1769, and enlarged the house there. A plan by Capability Brown for Barclay in 1770 introduced a serpentine lake. He sold it in 1793, after the death of his second wife, to William Cunliffe Shawe, and it passed in 1796 to Daniel Giles, Governor of the Bank of England. Barclay got to know John Scott of Amwell, that village being a few miles away, the other side of Ware; Scott was a fellow Quaker whom Barclay met on turnpike committees as well as at Friends' meetings. After Barclay had got to know Samuel Johnson through the Thrale brewery deal in 1781—Johnson being involved as an executor—Barclay approached him in 1784 to write the biography of Scott, who differed from Johnson in terms of politics, and in other matters.