[3] Barillon was often a conduit for pleas for clemency to Charles, (sometimes acting on the family's behalf, in which case he would accept money in return, but sometimes conveying King Louis's own view).
However these were not always well received; the King simply brushed aside his plea for the life of William, Lord Russell, and explained that while Oliver Plunkett, the Catholic Archbishop of Armagh, was certainly an innocent man, it was not expedient to spare him, for "My enemies are still waiting for me to make a false step".
[5] As a counterweight, he intrigued with the Whig leaders, notably Algernon Sidney, whose posthumous reputation was greatly damaged by the discovery that Barillon had paid him regular bribes.
Only once does he seem to have committed a serious diplomatic blunder: late in 1679 an indiscreet letter of his, reporting a conversation where Charles II claimed to have personally blocked a Franco-Dutch treaty, was leaked in the Netherlands.
[8] When it was rumoured in 1685 that the French had given tacit support to Monmouth's Rebellion, Sunderland told Barillon pointedly that he hoped this was a misunderstanding, or else the English would wonder if Louis had 'other plans they could not discern'.
[10] Barillon's privileged position was confirmed in the last days of Charles II's reign, when, alone among the diplomatic corps, he was allowed to send a secret message to Louis XIV that the King was dying.
James II's biographer describes him as an astute diplomat, with an ability to convey information through subtle hints, but he was personally a rather unattractive individual, being heavy, gross and boorish.