Having covered the Princess' wardrobe for more than a decade, I've witnessed the 'Kate Effect' countless times. Polka dotsLong favoured by the royals, polka dots were a defining feature of Princess Diana's wardrobe throughout the 1980s and 1990s. Her enviable collection is led by Alessandra Rich, whose vintage-inspired designs have become a signature of the Princess' wardrobe, alongside pieces by Emilia Wickstead, Rixo, Whistles and LK Bennett. Trouser suitsWhile floral dresses were once her go-to, Kate has increasingly gravitated towards trouser suits, favouring polished looks that reflect her evolving role. Coat dressesCoat dresses are synonymous with royal fashion, so it's no surprise they've become one of Kate's staples.