I think I know, what knickers are, but wouldn't my assumption likely be incorrect?
Are they 3/4 length pants, with a shirred cuff just below the knee?
Often worn for some type of sport activity?
As for jumpers, they were such a unique and helpful, very comfortable, layered type of a dress
worn on top of warmer turtle neck top,

That was way back
during the years when girls were required to wear dresses to school, regardless of frigid cold and whirling storms.
Can you believe I was reprimanded in kindergarten, for wearing leggings (snowpants)
to school in an extreme winter storm?
Obviously made to feel so badly, that I've remembered the teacher's reaction, all my life?
(Don't worry; I'm over it, now.

)