Now, there are no hard and fast rules about who counts, or what counts. So, I make these assumptions:
OK, so, here we go:
So, who are the longest serving companions?
In first place is Jamie McCrimmon on 119. As each new season is the equivalent of 29 episodes, it would take 4 seasons and 2 ordinary adventures to beat this.
In second place is Sarah Jane Smith on 91.
In joint third place are Barbara Wright, Ian Chesterton and Jo Grant on 77.
In sixth place is Tegan Jovanka on 70.
In seventh place is Amy Pnnd on 69.
In eighth place is Rose Tyler on 62.
In ninth place is Rory Williams on 57.
In tenth place is Susan Foreman on 55.