You can view Millie in her stylish leather trousers & buckle detail sandals here.
You can buy Millie's trousers here from the Muubaa website and her sandals here from the Net-A-Porter website.
Her pretty blouse in the photos linked above is from the brand Maje. I didn't include it in this post because I couldn't find it for sale anywhere.
Item images via Muubaa & Net-A-Porter.