Doctor Who: Every Tenth Doctor Episode Ranked From Worst To Best

School Reunion was a big deal for fans of the classic Doctor Who series, as it featured 1970s companion Sarah Jane Smith, and the loyal robot dog K-9.

While previous episodes of NuWho made occasional references to the Doctor's past incarnations - not too many at first, so the revived series could stand on its own two feet - School Reunion proudly acknowledges the classic series by serving as a direct sequel to it.

This episode could have overdone it on the fan service, but it somehow managed to find a healthy balance. This is epitomized in the moment where the Doctor has to awkwardly introduce Sarah Jane to Rose, while Mickey takes him to one side and states "The missus and the ex. Welcome to every man's worst nightmare!"

We're also treated to Anthony Head's delicious performance as a school headmaster who's actually an alien (because of course he is), though the less said about the aliens themselves, the better.

School Reunion barely puts a foot wrong, and it's all capped off with Sarah Jane finally getting the goodbye she'd waited decades to hear, which was a lovely way to end things.