The UK just hit these levels. Mississippi has been this poor a LONG time.

Plus - the economy of England is two countries: London, and the rest. Massive wealth disparities.

"Teacher numbers are falling"

Teacher's leave because of lack of pay and a bad working environments. Then schools decided to save money by not backfilling the position.

"provisions and resources seem to be"

cutting teacher resources = more money out of pocket for most teachers for their students. Another reason teacher numbers are falling.

"widespread delinquent behaviour has been reported to be on the rise,"

When parents lose hope and are struggling to survive what's the point of pushing education? When a teacher loses parental support, student behavior is one of the first things to get bad.

"and it seems like they’re refusing more and more to enforce the rules on such behaviour, but if you turn up with the wrong haircut or wearing trainers, all hell breaks loose. "

Admin and teachers are at a loss on how to reverse the student behavior trend. Without widespread parental support their hands are tied. So they find often focus on "coming down hard" on negative external trends they can identify, the so-called "gang-related" activities.

In addition to all the commentors talking about the actual funding of schools and pay for teachers. There is a well established link between the financial stability of a home and the performance of students that come from it. Struggling families have struggling students.

Social issues often are financial at their roots.

One word: underfunding. Pretty obvious really. Schooling costs money, and like anything else if there's not enough money to buy the stuff and pay for the people then corners will have to be cut, and corners can only be cut so far before quality suffers