Pupils who were caught smoking cannabis during their lunch break are likely to be expelled.
Sir Henry Floyd Grammar School leaders took the decision to exclude the pupils after a member of the public spotted them smoking the Class B drug off the school site.
An investigation was launched and involved looking at CCTV footage of the pupils.
The number of pupils dismissed has not been revealed by the school.
Floyd headteacher Stephen Box said: “A member of the public reported that they had seen some of our students smoking cannabis off the school site one lunchtime.
“The outcome was that we have recommended to our governors that a number of students be excluded.
“This follows the school’s behaviour policy, which is common to that of other schools in the area.
“We are determined to keep our learning environment safe for all students.”