A celebratory day for sixth-form leavers at St Clement Danes School has been cancelled, following a “serious incident” yesterday.

In an email to parents, seen by the Watford Observer, head teacher Dr Josephine Valentine told parents that year 13 students would not be allowed on site today.

She said: “Following a serious incident today involving Year 13 students, we have taken the decision to instigate study leave from 4pm today [yesterday].

“This decision has not been taken lightly, and we are aware that there will be a number of very disappointed students who have prepared certain activities for tomorrow.

“We deeply regret the disappointment of many students but due to the nature of the incident, there was no alternative.

“This decision took into account the well-being of the wider school community. This is a matter subject to on-going investigation by the school.”

One parent, who asked to not be named, said that the incident involved the vandalism of cars belonging to students from St Clement Danes and the Royal Masonic School.

A joint statement from Mrs Rose, Headmistress at the Royal Masonic School for Girls and Dr Valentine, said:

“Both St Clement Danes and RMS regret the ill judged behaviour of a small minority of students which has tainted the reputation of the year group as they approach the end of their life at school.

"Those involved have received sanctions in accordance with the each school’s code of conduct and the matter has been treated with the utmost gravity by both headteachers”.