Philip Pullman asks fans to help him find lost ballpoint he used to write His Dark Materials

Philip Pullman is appealing to the public in the hopes of finding the ballpoint pen he used to write all three books in his His Dark Materials trilogy.

The Oxford-based author posted on Twitter, writing that he'd "appreciate a tweet" if anyone recovers the pen.

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"Lost: a green leather pen case, containing a Montblanc ballpoint pen and an ordinary pencil," Pullman wrote.

"I'm particularly attached to the pen, because I wrote His Dark Materials with it. If anyone finds it, I'd appreciate a tweet."

The tweet, which at the time of writing has been retweeted over 4,000 times, has garnered the attention of fans — many of whom are offering to lend the author their own pens.

However, some Twitter users are a little more cynical about the likelihood of Pullman seeing the pen again — unless it's on eBay...

The His Dark Materials trilogy forms the basis of the BBC's upcoming TV adaptation, starring James McCoy, Ruth Wilson and 13-year-old Dafne Keen, who's set to play Lyra, a gutsy heroine with a talent for lying.

Fingers crossed Pullman finds his pen! If only he had an alethiometer going spare...