Responding after exam board WJEC was fined after more than 1,500 students last year received the wrong exam results, Sarah Hannafin, head of policy at school leaders’ union NAHT, said:

“It’s vital that students and school staff have trust in the qualification system and mistakes like this risk undermining that, as well as creating worry and stress for everyone concerned.

“Schools are charged a lot by exam boards and have in many cases seen increases in entry fees that are above-inflation and above increases in per-pupil funding - so the least they should expect is a dependable service.

“For all these reasons it is absolutely right that exam boards should be held accountable when they get things wrong, but more important still is that lessons are learned so that future student cohorts are not impacted by similar errors.”