“I think she would have been and outstanding grandmother,” he told PEOPLE in an exclusive new interview just before Monaco’s National Day on Thursday.
As for his father, the late Prince Rainier III, “He would have been a little more indulgent. More lenient than he was with myself and my sisters.”
• Want to keep up with the latest royals coverage? Click here to subscribe to the Royals Newsletter.
“Stephanie has come by more often than Caroline,” he reveals, “but that’s because Caroline is busy still, with her own daughter Alexandre. Stephanie came over yesterday to see the kids. Not to babysit, but if they want to volunteer for babysitting duty they’ll be most welcomed.”