Published Wednesday, 02 April 2014
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 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 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 children's charity.