Can You Guess the Celebrity in This Yearbook Photo?

Would ya look at this little Irish lass! Isn't she so darling in this yearbook photo? We are loving the tie and sweater, and her baby blues are really popping in this pic. 

Nowadays, this beautiful songbird keeps busy as one-fifth of a major British-Irish girl group, as a mom to her first child, and as a wife to a super hot rugby player. She's also a dancer and plays guitar, and sometimes you can catch her on E! as she chases her dreams with the other members of her singing group.