I believe this is an "English Medium School", but I put that in quotes for a reason. There are two types of English Medium Schools in Pakistan.

The first is a true English Medium School, where people become fluent in English. This is where people working at multi national companies would send their kids for school. The elite classes of Pakistan would also send their kids to these types of schools.

The second are, by name, also English Medium Schools, but cater to the local population who want their kids to know English (due to global mobility). The problem is that most of these schools don't have teachers who are fluent in English themselves. This, coupled with a legacy of colonialism, makes people feel they are "superior" for knowing English, and that those who only know Urdu are "ignorant". The irony is that they themselves really don't know much English, or can perhaps only read or write English.

The school in question appears to be in the second category.

Paradoxically, Pakistanis are very defensive regarding Urdu (they will often say it is "not the same as Hindi" even though linguists themselves say the two are essentially the same language).