JCoSS placed its students on early study leave last week to avoid potential misbehaviour arising from a pre-GCSE “muck-up” day.

Around 120 year 11 pupils at the school in East Barnet were sent home last Thursday, after rumours circulated that they were organising what would have been the school’s first ever muck-up day – when students starting exam revision are traditionally allowed to indulge in high-jinks.

Last week, 300 pupils at JFS were sent home after its muck-up day descended into chaos with school property vandalised and the headteacher verbally abused.

JCoss said it had made the decision before the events at JFS had taken place.

Headteacher Patrick Moriarty called it a pre-emptive measure, but insisted there was “no sense” that his students were capable of replicating the scenes at JFS.

He said: “We felt from our experience that the last day, muck-up day, can sometimes get a little over-exuberant and people can end up spoiling the good relationship we have with our students.

“We decided it a whole day before the events at JFS. We had no reason to think that anything was going to happen, but we thought it would be a more dignified way to end formal lessons if we finished a day early.

“They have very good relations with the school, but things can sometimes go wrong through high spirits and we didn’t want there to be that temptation.”

JFS headteacher Jonathan Miller has pledged that students who were involved in the “loutish and dangerous behaviour” at the school would be dealt with “in the strongest possible way”.

Videos of pupils damaging a security fence and road signs outside the school and swearing at Mr Miller were posted online.