We know her best as Ginny Weasley in the much-watched Harry Potter films but at the Cinema Against Aids Gala at Cannes Film Festival last week we saw a glamorous young woman (with incredibly chic dress sense!) in place of the child star.

In a bid to look classy with a touch of sultry sex appeal Bonnie chose a sophisticated long black dress with a deep-V neckline and a subtle leg-split that hinted rather than shouted about the actress' to-die-for figure.

If you've got a formal event coming up follow in Bonnie's footsteps with this classic look. With a few choice accessories: black and gold chandelier earrings, a bejewelled clutch bag and simple black heels, and this chic long black evening gown Bonnie's style makes a statement for all the right reasons.

Get the look at LittleBlackDress.co.uk:

Gorgeous Couture Rihanna Maxi Dress in Black, £172; Johnny Loves Rosie Leaf Drop Earrings in Gold, £16; Moda in Pelle Kacey Shoe in Black, £59.95; Aftershock Paolina Embellished Clutch Bag, £76.

Shop all long black dresses here.