The past and the future of Doctor Who collided tonight as 12th (?) Doctor Peter Capaldi made a brief but significant debut in The Day of the Doctor ahead of his full introduction at Christmas, while Tom Baker appeared as an enigmatic character who may or may not have been an aged version of the fourth Doctor.
Viewers saw only a glimpse of Capaldi's eyes but were left in doubt that they belonged to Matt Smith's successor. As 12 Doctors converged on Gallifrey, a Time Lord observed "No, 13!" and the forthcoming Doctor was seen with his gaze fixed determinedly ahead.
As the episode approached its conclusion, set in a London museum, Baker made his appearance as a character calling himself simply The Curator. In a rather emotional conversation with Matt Smith's 11th Doctor, the 79-year-old former Time Lord was enigmatic – but not that enigmatic – about whether he was there in his capacity as the fourth Doctor.
"Who knows?" he said, tapping the side of his nose, "Who nose..."