Robert and Thomas Wintour is written about the Gunpowder Plot is derived from Thomas's confession, signed on 23 November 1605; details of the so-called Spanish Treason were added three days later. One of only two confessions printed in the "King's Book" (a highly partial contemporary account of the affair), Thomas Wintour's was the only account the government had of a plotter who had been involved from the beginning; Guy Fawkes, weakened by days of torture, may have been at the heart of the group, but he was not at its first meetings. However, Antonia Fraser views the document with suspicion, not least because Thomas's
Robert Catesby the meeting is weighted with hindsight (when captured he sought to distance himself from the affair), he asked Catesby what support for the Catholics would be forthcoming once the king had been killed. Catesby's answer, "The necessity of the Catholics [was such that] it must needs be done", in Fraser's opinion demonstrates his unwavering view on the matter, held at least since his first meeting with Thomas Wintour early in 1604. The final conspirator to be brought in was Everard Digby, on 21 October, at Harrowden. Catesby confided in Digby during a delayed Feast of Saint Luke. Like Rookwood, Digby