Conn had no sooner arrived in England than the report was spread that he was a disguised Jesuit, come to receive the King into the Catholic Church. Charles, in terror of the Puritans, declared that it was a purely malicious invention, but none the less he continued to temporise, and the court to regulate its conscience according to his vacillating example. Some of the nobility were received into the Church, and among them Lord Boteler and Lady Newport. Mass was again said in the houses of the Catholic gentry.
In a letter to the Cardinal, written soon after his arrival, Conn gave an account of along conversation he had had with Charles, in the course of which he "remarked to his Majesty that the other powers of Christendom were extremely jealous of the relations which had begun to exist between the Apostolic See and Great Britain. They know," he continued, "that a perfect union between the two must necessarily tend to check their extravagances, and restore to Christ His lost patrimony in the west."
To this the King replied with some emotion, saying:
"May God pardon the first authors of the rupture."
"Sire," I answered, "the greater will be your Majesty's glory, when by your means so great an evil is remedied." To which the King made no further response. Not long afterwards, Charles asked Conn whether he considered it an easy thing for a man to change his religion.
"I told him," said Conn, "that when a man applied himself without passion or prejudice to find out the truth, God never failed to enlighten him." To which the King took in good part.
"I am obliged to proceed very cautiously," he added, "that they may not think the rumour of my coming here to receive the King into the Church had its origin in my presumption. It was a truly diabolical invention, and calculated to spoil everything."
If the Puritans were angry before, Conn's sojourn in England lashed them into fury. Rome's Masterpiece was written when his service had come to an end, and in the first flush of Puritan triumph. On its title-page it styles the mission "The Grand Conspiracy of the Pope and his Jesuited instruments to extirpate the Protestant religion, re-establish Popery, subvert laws, liberties, peace, parliaments—by kindling a civil war in Scotland and all his Majesty's realms; and to poison the King himself, in case he comply not with them in these their execrable designs."
This is how the "conspiracy" is said to have been discovered:—
"Revealed out of conscience to Andreas ab Habernfeld by an agent sent from Rome into England by Cardinal Barberini, as an assistant to Conn, the Pope's late Nuncio, to prosecute this most execrable plot (in which he persisted a principal actor several years), who discovered it to Sir William Boswell, his Majesty's agent at the Hague, 6th September 1640. He, under an oath of secrecy to the Archbishop of Canterbury, among whose papers it was casually found by Mr. Prynne, May 31, 1643, who communicated it to the king, as the greatest business that ever was put to him."