Robert Barclay, after whom Barclay Press was named, was one of the few “Quaker aristocrats” of the first half-century of the Friends movement. He was born to a wealthy Scottish family in 1648, brought up as a strict Calvinist, and educated at a Roman Catholic college in Paris where he became proficient both in Latin and French. Robert Barclay became a convinced Friend at eighteen years of age after visiting his father in prison and coming under the influence of a fellow prisoner, John Swinton, who was a Quaker.

With the benefit of family wealth, Robert spent a good deal of time in scholarship at the family estate in Ury. In 1676, at the age of 27, he published in Latin the work for which he is most famous, An Apology for the True Christianity Divinity, being an Explanation and Vindication of the Principles and Doctrines of the People Called Quakers. Barclay's Apology, as it's known today, is still the best and most thorough defense of Friends principles that has ever been written.

In addition to his scholarly work, Barclay made an extensive evangelistic trip to Europe with George Fox, William Penn, and George Keith and served for a time, in absentia, as governor of the colony in East Jersey. He and his wife are ancestors of the Barclays of the famous banking firm and the Gurneys of Earlham.