The girls at our school also had to wear gigantic grey knickers, prolly with a steel lining, for some reason 
We had to wear bottle green ones

We also had to make our own PE skirt in needlework in the 1st year at secondary school. Weren't allowed to buy one at all !!!
Until you finished the making the skirt you had to do hockey and the like in your knickers .
Compounded by the issue of the playing field being sited right next door to the Boys School and they had to walk past to get to their school entrance. Oh the trauma

Guaranteed you werked feckin hard in needlework - at least until you had made your skirt