I have got some of the Tesco ones. They were £12.99.
They are not leggings material but denim and are, as far as I can tell, skinny jeans with an elasticated waist and no pockets which tuck into boots properly and must be worn with a long top. In fact are to give a better silhouette under a long top than normal jeans, hence the lack of pockets.
But like someone else said I have to keep hoiking them up. I thought that was because I am between sizes.