My memories of the UK organisation ~
Like Heather, I was a member of Junior Red Cross in the UK in the late 1950s and 1960s. This covered the 12-16 age group.
As far as I can remember we wore pale blue cotton dresses. We met once a week for 2 hours. The first part was very formal, covering instruction in First Aid, Nursing and Midwifery. We were tested in each aspect and awarded badges if successful. I think I still have my badges somewhere.
After the formal session, we were taught various country dances!! Afterwards, we all went to the Fish and Chip shop and on to the Youth club!
It was an all female group. The male equivalent was St John's (Ambulance) cadets. I think the St John's group was mixed gender and they did wear the white shirt and black tie that has been mentioned. We didn't have a junior St John's in our village.
Gadget
Add - it was not school based.