Goose Island Linen Swirl Flower Dress in White (4256W).
 
One size would fit up to a UK size 16. 
 
"One size fits all" or "one size" clothing is a type of clothing that is designed to fit a variety of body shapes and sizes. This is achieved through several design and material choices:
 
Flexible materials
Loose or flowy designs
Adjustable features
Strategic cut and construction
Universal sizes
Styling

It's important to note, however, that while one-size clothing can accommodate a range of sizes, it may not fit everyone perfectly. The fit can vary depending on the individual's body shape and size.