I normally wear M and S cotton midi briefs, and sometimes (yes I know we're into big bum territory but I don't care - I like a warm back) their full briefs.
So last week I bought the same thing in tesco - £3.50 a pack of five mixed colours (half the price of M and S), and they are very comfy, in fact nicer than the Marks ones.
I give you this knicker info. entirely free of charge 