Wales Online have published an article about mixed sex toilets in Welsh schools, highlighting research from Lleisiau Merched Cymru that found that girls are missing school or refusing to drink all day so that don't have to use them.
www.walesonline.co.uk/news/education/pupils-missing-school-because-dont-15839558?fbclid=IwAR2uOXMN4LVJ6GaU7jO-yRYJ9D7_RQJvoV6TLnahB2eMdigAxtreVzke6eU
The comments section mentions that the doors can be opened from the outside making the girls even more vulnerable.