The Music and Lyrics star is currently busy promoting his latest film, The Rewrite, in which he stars as a struggling screenwriter who lands up as a teacher in an East Coast college.
But, as he admits, his ongoing work for the Hacked Off campaign, set up in the wake of the phone hacking scandal, has now become "kind of a full time job".
The 54-year-old gave evidence to the Leveson Inquiry, claiming that the Mail on Sunday hacked into his voicemails for a story about his former relationship with Jemima Khan.
So, with personal experience of hacking and intrusion, what does Grant make of the recent nude photo leaks?
"I think it's horrible," he told The Independent. "But I get frustrated because people seem to think the Hacked Off campaign is about intrusion into the lives of celebrities when it's almost nothing to do with that.
"It's much more about who runs the country and whether certain newspaper barons run the country. It's about their immunity and ability to abuse really vulnerable people who have lost children in accidents and things like that. So, celebrity privacy is a minor issue."
Model Daisy Lowe and Doctor Who star Matt Smith are the latest celebrity victims of the iCloud hackings, which began in August when naked pictures of actress Jennifer Lawrence, Cara Delevingne, Kate Upton and Jessica Brown Findlay emerged online.
Lawrence broke her silence on the hacking earlier this week, when she told Vanity Fair that it was "not a scandal but a sex crime".
"It is a sexual violation," she said. "It's disgusting. The law needs to be changed, and we need to change. Just the fact that somebody can be sexually exploited and violated, and the first thought that crosses somebody’s mind is to make a profit from it. It's so beyond me.
"I just can't imagine being that detached from humanity. I can't imagine being that thoughtless and careless and so empty inside."Reuse content