The Late Late Show presenter told the Herald how he found Alice Sebold's best-selling book The Lovely Bones too upsetting to read.
Accompanied by his girlfriend Aoibhinn Ni Shuilleabhain, he introduced the Irish premiere to hundreds of VIP guests at the Savoy cinema last night.
"I tried reading it but it was a tough setting -- a little girl who was abducted and I couldn't do it. So I abandoned the book and I'm going to watch the movie instead because I was invited to see it," he explained.
"Saoirse asked me to do this and I thought I couldn't let her down. She's been on the show a couple of times and as soon as I saw her in Atonement with her little clipped English accent, I thought 'a star is born'."
Other attendees at last night's premiere, followed by a party in Residence, included Morah Ryan with daughters Lottie and Bonnie .
Also spotted were Gay Byrne with wife Kathleen; Sarah and Emma Bolger; Gail Kaneswaran and Colette McBarron, Lisa Cannon and Rachel Kavanagh.