Princess Diana jokingly referred to her clutches as her 'cleavage bags'

Another day, another secret use for a famous royal's purse.

We know that Queen Elizabeth II uses her handbag to send signals to her staff and that Duchess Kate holds her clutch in both hands when she's attempting to avoid an awkward handshake -- and now, the hidden function behind Princess Diana's clutches has been uncovered.

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If you look at old photos of the Princess of Wales exiting cars at events, you'll notice that she's almost always carrying a clutch -- and the accessory didn't just exist to hold her belongings.

"We used to laugh when we designed what she called her 'cleavage bags,' little satin clutches which she would cover her cleavage with when she stepped out of cars," the royal's handbag designer Anya Hindmarch told the Telegraph.

See Princess Di with her "cleavage bags":

Well, the photos don't lie -- the trick seemingly worked like a charm. Smart, smart lady.