I just bought these from Peacocks yesterday. They're made to look like skinny jeans, but feel like quite thick stretchy legging material, so they hold your tum in and they're not see through like most leggings are.
I've had them on all day so far and they're so comfy. They're long as well - they reach down to my feet and I take a 32" inside leg.
The price on the site says £12 for some reason, but they're labelled at £14 in the shop.