Speaking in a behind-the-scenes video about his transformation, Simm revealed the heavy prosthetics, Dwarven-beard and new-fangled teeth fooled even his own eyes: “Every time I walked past the mirror I had a heart attack! I was like ‘Eugh!’ – you forget it’s on!”
A (heavily guy-linered) Simm also admits that his new goatee was meant as a small Easter Egg to fans: “I thought of it as a bit of an old school nod to old school master.”
And his facial fuzz homage to Who of old is one you’ll be able to enjoy in its full glory next week: the trailer for the series 10 finale shows The Master without his camouflage, facing The Doctor Time Lord to Time Lord in an epic Cyberman-packed showdown.
Bring. It. On.
The Doctor Who series 10 finale is on BBC1 Saturday at 6.45pm
Sign up to the Radio Times newsletter for the latest TV and entertainment news