Can You Guess the Celebrity in This Yearbook Photo?

Would ya look at this little Brit! Isn't she so darling in this yearbook photo, posing in one of her finest sweaters and a cute flowery blouse?

Nowadays, this pop starlet can be seen wearing a lot more makeup and a lot less clothing -- her signature look as of late seems to be thigh-high tights with combat boots and oversized jerseys, a far cry from her days as an angelic school girl. As one fourth of one of the U.K.'s sexiest and sassiest girl groups, however, the 20-something singer's hot new look suits her... and then some!

Have you figured out who this pop star is? Click through to find out!