Alexandra Burke looked every inch the glamourous star last night, as she was snapped leaving the London's Queen's Theatre in a sequinned black dress and broad grin. 

But earlier that evening, the 24-year-old looked a far cry from her usually polished-self as she took to the stage for a one-off performance of popular musical Les Miserables, in aid of Children In Need's POP Goes The Musical.

The British songstress adopted the costume of a peasant during the French Revolution, donning a ragged jacket and skirt, teamed with a skirt and tatty blouse pinned in place with a tan-coloured belt.

However, after her performance, Burke emerged from the venue dressed up in a super-short figure-hugging black dress, flaunting her toned legs and her pearly whites for the paparazzi.

The 'Without You' hitmaker is currently prepping to release her third studio album for release in the US.

Check out more pictures of Alexandra Burke after her theatre performance......

Robbie, Gary, The Saturdays & Alexandra Burke Light Up Heroes Concert