In photographs a divided skirt and ladies shorts are sometimes hard to tell apart. They were both of the same length; about three inches above the knee.
Divided skirts were seen as more feminine and thus more popular than shorts. Both choices allowed the wearer to have bare legs with ankle socks and tennis shoes.
The waistband was worn high, on or slightly above the natural waist.
Divided skirts could be bought ready made or adapted from the skirt from a winter suit .
Happy Moments at Mablethorpe date 1947 My Mum: born 1918
These days this garment we would call culottes.