- Video report by Martin Stew
Research carried out by ITV London found the number of arrests for the possession of cannabis in schools each year across London, Kent, Essex and Hertfordshire has nearly doubled from 112 to 220 in just five years.
There was also an increase in arrests for possessing and dealing other drugs such as cocaine and ecstasy.
Home Office statistics show in the same five-year period show the number of 11 to 15 year olds who admit to taking drugs has increased by 41%.
The number of schoolchildren getting drugs in school has gone up 27%.
Simone Gordon, who spent a year in a French prison when she was 19 for smuggling cannabis, said: "Schools are ignorant to it until its on their premises and it becomes their problem and then they call the police. That child now has a record, that follows them for the rest of their life.
"Demonising drugs isn't the solution to this problem."
Primary schoolchildren are now being educated about the dangers of drugs, something that was only previously part of secondary education.