The concept of changing your curtains with the season was new to me when I moved to the UK (and across the world) a year or so ago. Admittedly, it's not hugely common and was mostly done during Victorian times, but still — I wouldn't want to be caught out with breezy linen sheers when it's snowing outside.
So, what do you do when you love the look of linen, but require a style of curtain that's a whole lot warmer? You find something that gives you the best of both seasons, like these Thermal Curtains in Linen from La Redoute. Its clever two-layer construction means you get the light and breezy look of linen, while a patented "metallic technical lining" acts as an insulating barrier, keeping you (and your home) nice and warm.
