The comedian has been cast as a futuristic train engineer in an upcoming episode of the BBC sci-fi series – after angling for a part for some time.
And he confessed to What’s On TV that while he was thrilled to get the role, the fact he is such a huge fan of the show made him fear he wouldn’t do it justice.
“It was a strange mix between absolute, utter elation and terror,” said the star.
“I didn’t realise the pressure of being in a programme that you are completely in love with. Everything I did, I thought, ‘Oh no, that isn’t good enough for Doctor Who’.”
Shooting his part as Perkins alongside current Time Lord Peter Capaldi meant Frank missed being at his son Buzz’s second birthday party.
But he said: “Ultimately I thought he would probably rather have a dad who has been in Doctor Who than one who was at a second birthday he can’t even remember.”
via Press Association