The model and reality star thought she'd play it safe in all black but it seems she didn't realise just how sheer her roll-neck top really was when she stepped out in front of the paparazzi.
Oh, well hello there, cleavage!
Casey - who gave us all a good look at her black plunge bra - stood out in the spray-on, see-through number which she teamed with a little ra-ra skirt and a pair of grey thigh-high boots but we reckon she managed to own the slight wardrobe malfunction.
Yep, you read that correctly. The underwear as outwear trend is so totally in at the moment, anyway - just ask Khloe Kardashian and Love Island's Cara de la Hoyde!
Boobs aside, Ms. Batchelor's hair and make-up also made waves during the evening.
The Essex babe is famous for her big bouncy blow-dries but she ditched hours in the salon chair for a quick and easy ponytail ahead of the city party - and d'ya know what? We approve!
As always, Casey's contour and nude lip combo was seriously on point and she gave us a whole 'lotta brow envy, too.
The gorgeous star was joined by X Factor's Freddy Parker (who recently got the boot from the show), Imogen Thomas and Celebs Go Dating's Lady Nadia Essex at the bash - but it's safe to say she made the biggest splash - and yep, it's got everything to do with that top!
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