Ncuti Gatwa is opening up about why he left “Doctor Who” after only two seasons. In a new interview on the BBC’s “Sunday With Laura Kuenssberg,” the “Barbie” and “Sex Education” star was asked his reasoning for stepping away from the iconic sci-fi show.

Appearing on the Sunday with Laura Kuenssberg show, Gatwa initially gave his stock answer — heard previously as part of the official behind-the-scenes Doctor Who Unleashed documentary series, that the 32-year-old actor felt he was "getting old."

Doctor Who star Ncuti Gatwa has talked more about his decision to leave the series after such a brief stint in the TARDIS, and weighs in on the possibility of Billie Piper taking over as the