Plus one

Just prior to Earth Death in the year 5,000,000,000, the Ninth Doctor used his psychic paper to pass himself off as a guest, under the name "the Doctor", with Rose Tyler as his "plus one" to the steward of Platform One. (TV: The End of the World)

Aboard the spaceship Titanic, the Doctor to used the psychic paper to enter the Red 67 shore leave tour led by Mr Copper, with Astrid Peth as his "plus one". (TV: Voyage of the Damned)