N.B. there might (or might not) be spoilers in this article!

Strictly speaking untitled, but generally referred to as “Tonight’s the Night” (for the television talent show of which it was a part), this mini-episode is just a bit of fun, of course.

“Who the hell are you and what are you doing on the TARDIS?”

Captain Jack Harkness, Tonight’s the Night

It’s initially played for real (and, to be fair, laughs), with Captain Jack suspicious of the blue alien in the TARDIS who’s claiming to be the Doctor.

The intruder quickly admits to being an Aminopius named Sao Til, before yer actual David Tennant arrives on the set and we discover the blue alien is in truth Tim from Stoke-on-Trent (Tim Ingham, winner of the talent show).

Still, it’s worth it for the moment where Tennant slips into character to remind Cap’n Jack it’s his TARDIS.

His TARDIS.