The Barclay brothers used their insights into the North American situation as a guide to business strategy, first of all withdrawing from sales on commission, and then reducing their dependence on exporting across the Atlantic.

[8] Franklin's relationship with Quaker bankers went back 20 years, to his first English visit as agent for Pennsylvania: on that occasion he banked with Henton Brown's firm.

Brown had met Robert Hunter Morris as incoming Pennsylvania governor in 1754; and in 1755, along with Barclay, Bevan, Fothergill, and Capel Hanbury became a committee member concerned with the interests of the Society of Friends there.

Franklin, with Barclay and John Fothergill, drafted a plan to resolve the impasse existing after the Boston Tea Party of the previous year.

[12] Barclay met Lord North in 1775 to oppose moves against American access to fisheries, though without success, while Fothergill also worked behind the scenes.

Barclay approached his widow Hester Thrale the month after his death,[14] with a proposal to acquire a share in the business; this was much more welcome to her than the offer from the chief clerk, John Perkins.

[26] He and his brother had acquired Unity Valley Pen, a grazing farm in Saint Ann Parish, in return for a debt, and were discomforted to find themselves the owners of about 30 slaves.

Barclay wrote that when his brother died, "I determined to try the experiment of liberating my slaves, firmly convinced, that the retaining of my fellow creatures in bondage was not only irreconcilable with the precepts of Christianity, but subversive of the rights of human nature ...."[27] He hired a vessel to take them to America; his agent for the transfer, William Holden, was instructed to take them to Philadelphia and deliver them as emancipated to John Ashley, Barclay's agent there.

[34] He married twice, and had one child who survived to adulthood: Barclay supported the education of his grandson Hudson Gurney, which took place with his companion the polymath Thomas Young (two years older) at Youngsbury, from 1787 to 1792.