1605

Ian, Barbara, Vicki and the First Doctor arrived in England during the events of the "Gunpowder Plot". Following the collapse of the plot, Robert Catesby and Sir Thomas Percy fled to Holbech House in Staffordshire, where they were shot and killed by the Sheriff of Worcester's men. Also killed was the genuine Guy Fawkes. The time travellers' presence had slightly altered history so that Fawkes died a year early. Sir Robert Cecil, King James' chief minister, immediately seized upon the political opportunity inherent in a dead Fawkes. He labelled his political rival, Robert Hay, as Fawkes, which allowed for Hay's execution under the name "Fawkes" the next year. History thus healed itself. (MA: The Plotters)

But as another account suggests, the Eleventh Doctor, Rory, and Amy arrived to find Lady Winters (a Rutan in disguise) interfering with the event, and a Sontaran army trying to find a doomsday device owned by the Rutans. The Doctor gave them both a doomsday device, one triggered to the Sontarans and one to the Rutans. If one of them used it, they would not know rather or not they were killing themselves. The two armies left and history continued on its planned path. (VG): The Gunpowder Plot)