Princess Diana's teal ball gown
Back in the late 80s, Princess Diana and Prince Charles danced at a formal event and she opted for a teal one-shoulder ball gown.
MORE: 5 times Princess Diana gave us gym kit inspiration
Later series we'll expect to see her 90s outfits; her revenge dress, the dresses she wore as a single lady, and her love of particular designers shine through.
There's no set premiere date for The Crown Season 4 just yet, but as soon as HELLO! finds out, you'll be the first to know.