At a London film premiere on Thursday evening, the Duchess wholesale halloween costumes of Cambridge – whose Kensington Palace home is next door to Tamara Eccelstone's 57-room mansion – inadvertently copied the heiress by wearing a £320 white gown made by emerging designer Self Portrait.

Tamara wore the same dress for an Evening Standard photoshoot Halloween Costumes Outlet in June, as my picture shows, while American socialite Paris Hilton has also sported the gown.

Paris, 35, first wore the £320 pleated crochet floral maxi dress - which features a prominent slit in its long flowing pleated skirt - to the amfAR Inspiration Gala in Los Angeles.

It's a fashion first for the Duchess qwqfdvdsadf of Cambridge! Stepping out to the premiere of A Street Cat Named Bob, Kate wore a dress by Self-Portrait - the very first time she's worn this popular label.

Unless you've been hiding under a rock recently, you'll be well aware of Self-Portrait. Launched in 2013, the brand's signature lace dresses have gone on to be worn by pretty much every A-lister out there including Beyonce, Chrissy Teigen and Olivia Palermo to name but a few. In fact, we spotted Paris Hilton in this very same dress just last week!

Featuring a high neck top in the label's signature floral crochet, plus a pleated skirt, it's an ultra-elegant gown and suits Kate down to the ground.

The Duchess normally favours designers like Alexander McQueen and Jenny Packham when it comes to eveningwear but for £320, finally this is a red carpet look we can try ourselves! Click (right) now to snap up a two tone version.

For more Self-Portrait action, head to our edit below, plus check out our credit-friendly crochet picks from the likes of Club L and For Love & Lemons.

Other features of the dress include a modest high neckline countered by an intricate lace bodice.

Kate wore her hair down and red shoes, while Paris gave her look an LA twist by accessorizing the dress with dangling earrings, a jeweled headband and patent white stilettos.