Complex sentence: Pit brow women or pit brow lasses were the female surface labourers at the collieries who worked at the coal screens on the pit bank (or brow) at the shaft top until the 1960s.
Split into simpler sentences: Pit brow women or pit brow lasses were the female surface labourers at collieries. They worked at the coal screens on the pit bank (or brow) at the shaft top until the 1960s.