Kate Middleton, The Duchess of Cambridge, met Bob, the star of “A Street Cat Named Bob,” at the film’s world premiere last night at Curzon Mayfair, London.

Hello magazine reports that Kate was a bit unsure whether to pet the former homeless feline.

“He’s being very good,” she said as the feline – who wore a red and black scarf for his red carpet debut – paid her no attention her while looking distractedly at the cameras.

She then joked: “Is that purring or growling?” leading his owner James Bowen, whose life with Bob inspired the best-selling novel and the film adaptation, to check the pet for himself, replying: “I’m not really sure if that’s purring or growling,” before putting a hand on Bob just in case.

The premiere benefited Action on Addiction.

“A Street Cat Named Bob” is based on Bowen’s memoir about his days as a homeless addict and his unlikely friendship with a stray ginger cat named Bob who changed his life. “He gave me a reason to get up in the morning … and now I’m standing here,” Bowen told Reuters on the red carpet with Bob perched on his shoulders. “A movie about a part of our lives is just mind blowing.”

Luke Treadway (“Clash of the Titans”) stars as Bowen in the film while Bob, naturally, plays himself. Costar Joanna Froggatt (“Downton Abbey”) described Bob as a “professional” on set.

The film costars  Ruta Gedmintas (“The Strain”) and Anthony Head (“Buffy the Vampire Slayer”). Roger Spottiswoode (whose films include “Turner and Hooch” and “Midnight Sun”) directed.

The movie is now playing in the UK and opens in the US on November 18.