While I am not female, I was educated in a co-educational school in the UK and took an intelligent interest in the subject you raised as part of my education.
The garment in both my secondary schools was navy-blue and tight, generally just covering the underbuttocks and clutching them. Navy-blue was the common colour though not the only one: various memoirs have referred to bottle green, and I remember girls from another school arriving for some athletics competition and competing in dark red knickers. Later, the knickers while mostly still navy blue became stretchier and shorter (different material, I assume, to the rather rough cloth) and tended to expose slivers of underbuttock on the portlier bottoms, especially if the girl bent.
Certainly at my first school the P.E. knickers (that was the term rather than gym, as gym implied indoor activity and P.E. could be indoors or outdoors) were identical to those required by school uniform regulations for normal dress, though whether girls changed into a spare pair for P.E. and Games, I don't know. If they didn't, they could have been sweaty or damp or muddy (from outdoor events) for some time afterwards, so my guess is they changed. From memory, I think in my second secondary school the uniform regs must still have required navy-blue knickers up to the point a strict uniform was replaced by broad guidelines, though certainly some girls wore something else. P.E. and Games, though, were still done in navy-blue knickers.
These were often worn under a very short, rather rigid navy-blue skirt called the gymslip, a famed fantasy item, though I think most boys regarded them as a bit of a killjoy. More often, though, no gymslip was worn and girls carried out their tasks or play in knickers and loose white vest (the term over here in my time was vest rather than singlet), or in colder weather, with a navy blue thin woollen jersey or suchlike over the top but not covering the knickers.
Girls did not, of course, actually report for P.E. or Games in this garb only, as they'd come from other lessons fully clothed and change in the changing-rooms, an area of much juvenile fantasy.
Adult versions of the gymslip were also sometimes worn by female P.E. and Games teachers. I have no information about what they wore under them. |