His last visit to London was early in 1688, and he remained all the summer. On the journey he had the company of his brother-in-law, Sir Ewen Cameron, of Lochiel. He took with him his eldest son Robert, then a boy of sixteen, remarkable alike for his piety and for his precocious Scotch prudence, and introduced him to the court at Windsor. There he remained for some time, "being much caressed, it is said, on account of his father's interest, which occasioned numerous dependents; and he appears to have conducted himself so as to incur no reproach even with Quakers." A sermon which Robert Barclay preached at this time in Gracechurch St. Meeting, was reported and has been published. One great object of this journey was to see justice done to his brother-in-law, who had a difference with the powerful Duke of Gordon. Barclay set himself in good earnest to get the matter righted. First he wrote to several English noblemen with whom he was intimate, but they were shy of the difficult task, though they all professed their willingness to help him in anything else. Then he appealed to the king, and "succeeded in obtaining from him a full hearing upon the whole matter, in the presence of the Marquis of Powis and the Earls of Murray and Melfort, who were requested to become referees. Persevering through all obstructions raised by the opposite party, Barclay was able at length to obtain a final settlement, much to the advantage of Cameron of Lochiel." Thus again James appears under Barclay's influence as the good genius of the oppressed. On one of his visits to the court, he found the king full of the thought of the coming of the Prince of Orange. They had a serious conversation about the state of affairs, and Barclay, like Penn, sincerely sympathised with the royal culprit in his troubles. "Being with him near a window, the king looked out and observed that 'the wind was then fair for the Prince of Orange to come over.' Robert Barclay replied, 'it was hard that no expedient could be found to satisfy the people.' The king declared he would do anything becoming a gentleman, except parting with liberty of conscience, which he never would whilst he lived." After the Revolution, the calumnies by which he was assailed led to his drawing up a "Vindication," which is the last known production of his pen. For himself he would have been content to bear these calumnies in silence. Two reasons overruled this choice. Some men of judgment who found how completely he could refute them, wished his answers to be well known. On the other hand, the loss of his reputation caused damage to the Society to which he belonged, and of whose interests he was so jealous. Yet his own contempt for the charges laid against him, and for the popular opinion of him, is evident in almost every paragraph. There is more than courageous outspokenness; there is the indifference of one who feels, "With me it is a small thing that I should be judged of you. He that judgeth me is the Lord."