Private school; officially owned by a non-religious Association but suspiciously full of Jesuits, priests from other orders (one of my teachers while I was there was a Filipense, there was also a Franciscan but he wasn’t one of my teachers) and nuns (from two different orders). Most students had lunch at home, about 20% at the school and a tiny minority (all boys) were boarders.
The ownership has to do with the history of the Spanish Republics: both of them forbid “people belonging to religious organizations” from teaching. In a country in which it was religious orders who first opened primary schools, and in which most of the educational centers of the time(s) were owned by religious orders, this was not a particularly bright idea - but one of the consequences is that many schools with names such as “St Francis Xavier”, “St Jeanne de Lestonnac” or “Don Bosco” are not, I repeat, not, in any way, owned by religious orders. Seriouslyyyyyy! They’re owned by Funds or Associations which share the school’s name. In this way, those schools which had already set up such a fund by the time the bans and expulsions of the Second Republic rolled by were able to stay open, although with less teachers.
The school was and is under the financing mode known as “concertado”: they receive funds from the government, thus they have to follow the general curriculum more closely than an independently-funded school (of which in Spain there are very few). They can add to the curriculum but not take anything away or reorganize what has to be taught in each year (except by teaching it earlier, and this only for some subjects such as foreign languages, they can’t do it for Math or Spanish).