Young man (The Time of the Doctor)

From Tardis Wiki, the free Doctor Who reference

A young man was an inhabitant of Christmas towards the end of the centuries-long Siege of Trenzalore. On the last day of the siege, he came to warn the dying Eleventh Doctor that the Daleks had arrived and that there was nothing they could do. The Doctor mistook him for Barnable, a child who lived in Christmas centuries ago, and falsely assured him that he had a plan, saying later to Clara that the people of the town loved it when he said that. (TV: The Time of the Doctor)