Katherine Jenkins is polka dot pretty in her dress and blonde locks at the Audi Polo Challenge. If there was a strong, skirt-ruffling wind then she would have had a Marilyn Monroe moment in her sizzling frock.

Katherine Jenkins, Samantha Barks, and Gemma Arterton in their best day time dresses.

33-year-old "Dancing with the Stars" runner-up Katherine Jenkins sashayed onto grassy grounds at Coworth Park Polo Club in Ascot to watch Prince William and Prince Harry compete. The Welsh mezzo-soprano looked sexy without trying too hard. It was a backless, halter-neck dress for Katherine Jenkins. Her breezy dress with contrasting waistband and hem fit her just right. Excellent footwear choice as Katherine's nude t-strap cork wedges made for a great leg-lengthening trick. Katherine styled her bob in loose curls and added bright, red-orange lip colour.

Gemma Arterton was all about the bow. The British actress joined Katherine Jenkins at the Audi Polo Challenge. The "Runner Runner" star wore a blue, fit-and-flare Burberry dress with a bow embellished neckline and wide shoulder straps. It was a tad wrinkled, but Gemma's pleated skirt dress still painted a pretty picture. Minimal makeup, a loose updo, and nude t-strap pumps completed Gemma's day time look.

Katherine Jenkins is polka dot perfection, but Samantha Barks takes the best dressed spot at the event. "Les Miserables'" Eponine looked fabulous in ecru. Like Gemma, a fit-and-flare silhouette was Samantha's pick. Her sleeveless dress clung to her figure, showing off that famously tiny waist. The talented performer made up for her dress' subtle colour by pairing it with fun aqua-coloured pumps.

Model Lily Cole also joined the fun, posing alongside Dominic Cooper of "Captain America: The Winter Soldier." Even with a glittering, gold Isabel Marant mini skirt, Lily still looked quite dressed down with her white t-shirt and well worn cap-toe ballet flats.

The Audi Polo Challenge was in support of SkillForce and the Royal Marsden Cancer Charity.

Click on the photo for Gemma Arterton and Samantha Barks, and to see why Katherine Jenkins is polka dot pretty at the Audi Polo Challenge.

For more celebrity style, read:

Katherine Jenkins Shines at the Queen's Coronation Festival Gala [PHOTOS].