If you're looking for a heavy or warm duvet cover, this thin cover won't work for you. The insert is held in place by corner ties, side ties and a large zipper at the bottom -- an uncommon but ...

And it's currently on offer in the homeware store's sale The Dorma Meadow Breeze Duvet Cover and Pillowcase Set comes with a zipper fastening to ensure it remains securely in place once on the bed.