Tegan was the longest-serving companion in terms of years on the series ( 3 years , 1 month ) , although Jamie McCrimmon was in the most episodes and stories . Tegan was the longest-serving companion in terms of continuous years on the series ( 3 years , 1 month ) , closely followed by Sarah Jane Smith ( whom Tegan briefly meets in the serial The Five Doctors ) . Jamie McCrimmon was in more episodes and serials than Tegan , while Rose Tyler was in more serials , but not as many episodes .