The zones were launched by Alain Savary, education minister of the socialist government of 1982, to reduce social inequalities “to give more to those who have least”, as the slogan put it. ZEP schools receive about 10 per cent extra state funding, which translates into smaller classes, extra hours on the timetable and more teachers, who are paid a bonus for working in them.

In 1982, 8 per cent of primary pupils, and 10 per cent of lower secondary children, attended ZEP schools. Today, 1.8 million pupils, representing 15 per cent of primary and 18 per cent of lower secondary pupils are taught in 7,700 ZEP schools. More than 60 per cent come from disadvantaged families, compared with 39 per cent in schools outside the zones.

But while the zones are integrated into the education system, their 20th anniversary has highlighted mixed results and attitudes regarding their performance. National assessments show that ZEP-educated pupils score worse overall than those in “normal” schools, although supporters claim that pupils’ social backgrounds are an important factor and there are no evaluations on how schools would have performed without ZEP resources.

Ministry research found that “adapting to pupils’ levels” could pitch teachers’ expectations too low and widen disparities, but another study revealed that lower secondary pupils in ZEPs who did not switch school made as much progress as non-ZEP children.

Public opinion is divided. Ardent republicans protest that positive discrimination contradicts France’s tradition of equality, while many parents see ZEP as a label signifying schools to be avoided.

But when the ZEP status of successful schools was threatened, overwhelming pressure from teachers and parents who did not want to lose the extra resources resulted in another thousand schools being added to the educational priority system.