[5] He remained at Cambridge to read for a PhD in solid state physics,[6] with his proposed thesis, Novel quantum effects in low-temperature quasi-zero-dimensional mesoscopic electron systems.

[7] His interest in comedy began when a friend asked him to help chauffeur the judges of the National Student Drama Festival, which was being held that year in Cambridge.

[9] Having already finished his degree, he joined the Footlights in 1989 and worked with Andy Parsons, David Wolstencroft and Sue Perkins before he directed a revue.

[16] In 2003 he played the role of Bough, sidekick to Rowan Atkinson's title character, in the film Johnny English.

[citation needed] Miller provided the voice for the ITV Digital and later PG Tips Monkey in a popular series of television advertisements featuring Johnny Vegas.

[19] In 2008, he appeared as television producer Jonathan Pope in Tony Jordan's series Moving Wallpaper on ITV1 and starred in Thank God You're Here.

On 23 July 2012, Miller began touring for his book, It's Not Rocket Science, from the Royal Society in London.

Miller explained he had personal reasons for the change: "It was the job of a lifetime, but logistically I just didn't feel I could continue.

[30] In 2015, following the 800th anniversary of the Magna Carta, Miller starred as King John in Series 6 of Horrible Histories.

In 2016, Miller co-presented the ITV entertainment series It's Not Rocket Science alongside Rachel Riley and Romesh Ranganathan.

In February 2016 Miller issued a book, accompanied by a lecture tour, entitled The Aliens are Coming!, examining the question "are we alone in the universe?

"[31] That year, Miller played the role of Murray in the six-part BBC sitcom I Want My Wife Back, starring alongside Caroline Catz.

In 2018 he returned to the role of 'Bough', sidekick again to Rowan Atkinson's title character, in the film Johnny English Strikes Again.

[citation needed] He co-wrote MindGym, winner of the first BAFTA Interactive Entertainment Award for comedy in 1998, with Tim Wright and Adam Gee.

[40][failed verification][citation needed] In 2021, with the cast of Bridgerton, Miller received a nomination for the Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series.