Robert and Thomas Wintour the continent and again failed to elicit Spanish support, but instead met Guy Fawkes, with whom he returned to England. Robert, a devout Catholic who inherited Huddington Court near Worcester, joined the conspiracy the following year. The plot began to unravel following the delivery of an anonymous letter to William Parker, 4th Baron Monteagle, warning him to stay away from Parliament. Thomas and Catesby confronted Monteagle's brother-in-law, the recently recruited Francis Tresham, threatening to kill him, but Tresham managed to convince them of his innocence. At that stage Thomas reportedly asked Catesby to abandon the scheme, to no avail. When
Robert and Thomas Wintour attempted to dry their soaked gunpowder in front of the fire, only for a stray spark to ignite it. While Littleton chose to leave, begging his companion to follow his example, Thomas continued on to Holbeche, where he found the remaining plotters alive, but injured. While several including Robert and his half-brother John chose to vanish into the night, Catesby, Percy, the Wright brothers, Grant, Rookwood and Thomas remained. Thomas asked them what they intended to do – "We mean here to die". Thomas replied "I will take such part as you do". Richard Walsh, Sheriff of Worcester, arrived with