Where I live near London same sex children have to share indefinitely, the recommendation is until 16 but I know of 3 female siblings over the age of 16 having to share as the council expect them to use the living room as a bedroom and wherever can fit a single bed. Opposite sex children only until 10 years old, and although it’s not a huge priority to councils so takes some time, they will house families to a bigger property otherwise they are breaking their own rules. When my friend was trying to exchange her property from a 2 bed to a 3 bed they refused to put it through and told her she can only have a 4 bed as it’s 2 children per room overall and then age and sex breaks it down further, she has a 15 year old girl, 13 year old boy, 6 year old boy, 2 year old boy. No wonder there is a housing crisis but I think it’s not right for opposite sex teenagers to share a room, younger children I don’t see an issue with. The radfords wouldn’t care because their children’s mental health isn’t a priority. I had to share with 4 siblings and never had any privacy growing up, it was awful so I wouldn’t intentionally have children I couldn’t make space for.
Private rented or owned properties are exempt from that rule.