Prelax

Prelax was a planet which the Fifth Doctor, Peri Brown and Erimem visited. There was a costume ball which the Doctor tried to dissuade Peri and Erimem from attending, but they went anyway. Peri planned to wear Leela's outfit, but decided against it. In the meantime, the Doctor had to escort the Grand Dowager back to her palace. (BFA: No Place Like Home)