Oxford author Philip Pullman has revealed that he had to rehearse hard for a surprise cameo appearance in the play based on his award-winning fantasy trilogy.

Mr Pullman starred in the production of His Dark Materials, on the opening night of a run of performances at Oxford Playhouse, in Beaumont Street.

He appeared as an Oxford scholar in the play, and was on stage for 10 minutes in the non-speaking role.

Coming off stage on Wednesday night he said: “It was enormous fun. Even though I didn’t have a huge part, I was rehearsed within an inch of my life.

“The audience were very warm, which made it less nerve-racking, and the actors were wonderfully supportive.”

Mr Pullman, 62, who lives in Cumnor, was asked to take part in the play’s first night at the Playhouse after attending its opening in Birmingham last month.

He said: “I hadn’t thought about it until then, but when they asked me to take part, I realised I had a burning ambition to be on the stage.”

When asked if it was the start of a new career, Mr Pullman replied: “Who knows!”

The writer praised the Playhouse for “squeezing such a large cast and complicated set on to the stage”.

He added: “I haven’t done much acting since my days as an undergraduate at Exeter College, when I had a small role in As You Like It, and One Way Pendulum by NF Simpson.”

The audience was not told that Mr Pullman would be taking part and the only clue they had to his identity was when his character was congratulated on his books.

The appearance is expected to be a one-off.

Sarah Esdaile, director of the Birmingham Repertory Theatre production which finishes on Sunday, said: “We knew that Philip had really enjoyed the production, but it was a real thrill to see that he was so pleased he wanted to actually take an acting part.”

Last year, Mr Pullman was at the forefront of a successful campaign opposing a flats development on the former Castle Mill boatyard site in Jericho.

He is working on a follow-up to the His Dark Materials trilogy, which has a working title of The Book of Dust.

The His Dark Materials, from the mid-1990s, sold across the globe, and the trilogy was then adapted for the stage and cinema.