These are lovely snuggly tights, definitely warmer than normal ones as they are fleecy inside. They are made by BHS according to the label. I also have some similar tights by La Senza and although these tights are not properly skin tight around the ankle, they look better on the ankle than the La Senza ones.
The reason I've only given them three stars is that they are too short. To be fair, I'm quite tall (5' 9" ish) so have quite long legs, but they're on the skinny side (I take a size 8) and even though I ordered the med/large, they are too short. I have to pull them up really hard to get them to go on properly and really annoyingly, I managed to ladder them whilst doing this.
So if you are not sure which size to go for, unless your legs are on the short/petite side, I would size up.