Radcliffe was named Best Actor in a Play for his role in The Cripple of Inishmaan, while his former co-star took home the Newcomer of the Year Award for his West End debut in a revival of Mojo.
Ironically, Radcliffe previously won Grint's award in 2008, following the success of his stage breakthrough in Equus.
Other winners at the Prince of Wales Theatre awards ceremony in London included Dame Helen Mirren, who was named Best Actress in a Play for The Audience, which also landed the Best New Play; David Walliams, who picked up a Best Supporting Actor for his role in A Midsummer Night's Dream, which was named Best Shakespearean Production, and The Book of Mormon, which dominated the musical categories and came away with four awards, including Best New Musical and Best Actor in a Musical (Gavin Creel).
Scarlett Strallen's turn in A Chorus Line earned her the Best Actress in a Musical honour. The production also won Best Ensemble Performance. Haydn Gwynne was also a winner - she scored a Best Supporting Actress in a Play award for her portrayal of Margaret Thatcher in The Audience.
Meanwhile, Matilda the Musical was honoured with the Best West End Show title and Australian entertainer Barry Humphries (aka Dame Edna Everage) was handed the Best Solo Performance prize for his Eat Pray Laugh! show at the London Palladium.
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