The one and only John Barrowman - aka Captain Jack Harkness - has been a Doctor Who fan since he was a young kid, so actually getting to appear in the show was something of a dream come true for him.
Because of this, he had "a little weep" the first time he saw his name in the iconic opening title sequence, which first happened two episodes earlier, in Utopia.
Of course, Jack had appeared in Doctor Who a few times before then, but in those cases, he wasn't credited in the opening title sequence - just in the end credits.
Video and content editor at WhatCulture. Perpetually waiting for the next Christopher Nolan movie.