They went out at around 2pm and missed a lesson period in protest against plans to introduce an assembly on a Friday that will extend the school day by 15 minutes.

The other main change being planned from September is to introduce tutor groups for each year group.

A resident from Holmesdale Road, close to the school, said: "I first heard a lot of noise and saw pupils running out like sheep. They were chanting but I couldn't hear what it was all about."

One Year 9 pupil told the Mid Sussex Times: "We're unhappy because we leave at ten to three on a Friday, now we won't be able to leave until five past three. We've been told we have to tie our hair back and the boys can't wear hair gel. W

"hy can't they let us be ourselves? Just because we wear our hair long doesn't mean we can't learn."

Deputy head teacher Rob Corbett said: "There were a whole range of things that were not to do with the pastoral situation but were to do with uniform, none of which were true but gossip fed gossip and some of the pupils felt they needed to protest.

"It's important they had that opportunity but it's also important they find out the true facts."

He said some pupils had already been to assemblies explaining the pastoral changes but year ten pupils who had not had an assembly yet heard rumours and decided to protest.

He said: "I have taken note of who they were and I will be inviting them personally to a meeting with me after school on Monday so we can discuss any concerns they have."

He said the changes to tutor group structures and the addition of a Friday assembly were designed to help teachers to concentrate their skills on year groups to raise achievement.