Before we recommend new products, we always ask our trusted Mumsnet users, of which there are more than seven million each month. That’s a lot of honest, impartial advice. Expert guidance Our favourite features? This is the perfect onesie for Harry Potter lovers, complete with inner lining in Gryffindor’s iconic colour scheme. Our favourite features? Perfect for keeping warm at your desk, lounging in of an evening, or even using as nightwear, this is a versatile onesie that will see you right through winter.

As Martin Lewis said, it’s easier to heat the person than the home, so if you’re home alone during the day, rather than spending money heating the whole house, it’s worth layering up in a onesie to conserve warmth. As Money Saving Expert Martin Lewis keeps saying, it’s easier to heat the person than to heat the home, and wrapping up in a onesie when you’re the only one home is more cost-effective than blasting out the heating. It has a slouchy fit, so you can wear pyjamas or thermals underneath when the temperature really drops.

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Still, these are not the most breathable base layers we tested, which is one reason why we recommend them for lower-output activities, like light hikes, dog walks, and trips to brunch. That said, even with the higher cost, our tester still highly recommends them for lounging on winter days and for light activities. Our favourite features? Extra points go to this luxury onesie because if you’re on a video call, it could be mistaken for a chic top, meaning no colleagues need know that you’re cosy in your loungewear.

Merino wool isn’t the same as the kind your grandma uses for knitting. It’s very soft and comfortable. That said, testers who were extra sensitive to itchy or irritating fibers did report some issues with a couple of the merino wool thermal underwear sets we tried. If you tend to get irritated by wool, opt for a synthetic alternative like the Under Armour option above.Our favourite features? If you want a warm, snuggly onesie which can also double as fancy dress option, look no further!