Doctor Who: Every Series 2 Episode Ranked Worst To Best

What happens to the companions who are left behind? That was the core pull of this Series 2 story, where the Doctor infiltrates a school to take down the shapeshifting Krillitanes.

Sarah Jane and K9’s welcome return is a fantastic hook that adds to the universe, rather than just acting as a throwback for throwback’s sake. It’s not all a celebration - there are uncomfortable conversations to be had between characters both new and old.

School dinners and returning characters give this episode a nostalgic air, an adventure of childlike wonder as students’ brains are forced into solving the great equation of the universe. Not to mention Anthony Head as a sort of Demon Headmaster figure, chewing scenery and wide-mouth screaming with abandon, making full use of the role.

School Reunion may sit firmly in the middle of this list, but it's a fantastic example of Doctor Who’s range. It begins as an odd, quirky little set-up with Tennant posing as a teacher, and then ramps up to dire consequences, and questions about the morality of the Doctor’s choices.