The 24-year-old showed off her new 'do on Twitter with the caption: "I blame Sienna."
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Hours earlier, she had shared a picture of herself sweeping her long hair across her forehead – trying out how the style would look. "Thinking about getting a fringe cut...to chop or not to chop?!!": Read the caption.
The Quality Street heiress is getting back to everyday life after returning from her romantic honeymoon with Professor Green.
The pair went to Italy, and Millie's husband – real name Stephen Manderson – took several snaps of his new wife, which she in turn shared with her fans.
In one, she can be seen standing on the edge of an infinity pool, with a breathtaking view of the Italian coast behind her. The Made in Chelsea star shows off her slender figure in a leopard print bikini.
Another holiday snap shows her posing on the deck of a boat in a black one piece. The tweet accompanying the picture says: "Another day, another swimsuit."
In a final photo, the pretty blonde runs down a cobbled street wearing a white dress, her hair flowing out behind her. The caption simply says: "Memories."