What’s a rounded education? Mine, at private, study 2 languages, do drama, art, learn and play instruments in bands and the orchestra, played rugby nationally, represented the school in the swim team, went on overseas trips and their friends are from every corner of the world. My son’s group of friends include Europeans, Indians, an Egyptian, someone from Uzbekistan and someone from China. Their GF’s from school are Japanese and Italian.
Mine at a comp that's been in and out of special measures also study two languages, drama and art, Learn and play instruments in bands, the orchestra and in festivals including some overseas, played football for the school, swim for the school, represented the school in various STEM competitions, record audio books for blind people, represented the school as part of the eco club. They too have friends from all over the world.
They also have friends who's parents don't give two hoots about education, and they are in classes with some who are interested and engaged and others who are disruptive and don't want to be there, they have friends who are financially secure, friends who live in bed and breakfast accommodation.