The gunpowder conspirators. Facsimile of a contemporary print of the plotters involved in the 1605 conspiracy to blow up the English parliament. A small group of Catholics, disaffected by the anti- Catholic line taken by the new monarch, James I, rented a building with a cellar under parliament. Led by the charismatic Robert Catesby, they filled the cellar with gunpowder, ready to blow up parliament when the King opened it in October 1605. But its opening was delayed for a month due to the plague in London, by which time they had been betrayed by one of their number. The foiling of the plot is celebrated on the 5th November, bonfire night, in England.