British pop star Lily Allen showed off her risque side on stage at London's Royal Albert Hall on Tuesday night (01Apr14) by donning a translucent top and nipple pasties for a charity concert. The singer, who is carving out a music comeback after taking time out to have two children, captured fans' attention at the City Rocks charity gig in the U.K. capital with her controversial costume choice. Allen donned a vintage outfit, which included a see-through top exposing her bare breasts. She preserved some modesty by covering her nipples with stick-on pasties. Taking to Twitter.com after the show, Allen shared snaps of her racy ensemble with fans, writing, "RAH (Royal Albert Hall) tonight at Cityrocks (sic), in (vintage clothing store) @williamvintage amazingness (sic). With a side of boob." Sophie Ellis Bextor, The Feeling and Queen legend Brian May also took to the stage at the concert, which raised funds for Coram, a U.K. children's charity.