In 1586 Watson became a Roman Catholic priest in France, and during the concluding years of Elizabeth's reign he paid several visits to England; he was imprisoned and tortured more than once.
He became prominent in the Archpriest Controversy as a champion of the secular priests in their dispute with the Jesuits, and in 1601 some writings by him on this question appeared which were answered by Robert Parsons.
[2] When Elizabeth died, Watson hastened to Scotland to assure James I of the loyalty of his party, and to forestall the Jesuits, who were suspected of intriguing with Spain.
The new king did not, however, as was hoped, cease to exact the fines on recusants; and the general dissatisfaction felt by the Roman Catholics gave rise to the "Bye plot," or "Watson's plot," in which connection this priest's name is best known, and to its sequel the Main Plot; Watson discussed the grievances of his co-religionists with another priest, William Clark, with Sir Griffin Markham and Anthony Copley, and with a disappointed Protestant courtier, George Brooke; they took another Protestant, Thomas Grey, 15th Baron Grey de Wilton, into their confidence, and following Scottish precedents it was arranged that James should be surprised and seized, while they talked loudly about capturing the Tower of London, converting the King to Catholicism, and making Watson Lord Keeper.
[1] One or two of the conspirators drew back; but Watson and his remaining colleagues arranged to assemble at Greenwich on 24 June 1603, and under the pretence of presenting a petition to carry out their object.