When we first saw these pictures, we thought the 'Bad Romance' singer had actually stepped out sans bra, with boobs on show, but on closer inspection, she's actually wearing a teeny, tiny bra top.
Gaga was partying at The Box nightclub in Soho on Monday evening (9 June), after paying a visit to a Philip Treacy Hat shop.
Earlier in the evening, she'd met Prince Harry – and worn a rather more demure outfit for the occasion!
Gaga rubbed shoulders with the royal ahead of her performance with Tony Bennett at a WellChild charity concert in London. Prince Harry is a patron of the organisation, which provides help and support for sick children and their families.
According to the Evening Standard, the prince and Gaga got on famously, with Gaga calling him "fantastic" and saying: "We are so happy to be here tonight and be of any help."
Gaga and Tony Bennett, 88, have collaborated on an album of duets. Tony was friends with Harry's late mother Princess Diana.
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