Our school uniform was a navy gymslip and cream blouse. The gym slip had to be 9 inches above the knee when kneeling. OK for the younger girls but for the 18 year olds not so good. They wore stockings and the tops used to come below the hem of the gymslips. Lots of men used to line up on the edge of the grounds to stare at the stocking tops and suspenders.
To think that London, or anywhere else for that matter, does not belong to any one demographic