Campaigners for the legalisation of cannabis were today marching through the streets of London.
Organisers the International Cannabis Coalition stress that the demonstration was to be a peaceful protest to end the prohibition of cannabis.
Artist Caroline Coon, a guest speaker at the event, said: "If you make drugs like this outside the law they become exciting to young people.
"It is difficult to educate them about the dangers of something which is illegal and so there is a higher risk that they will secretly go on to try hard drugs with disastrous effects.
"London mayor Ken Livingstone wants to get drug dealers off our streets. But by banning drugs you just drive dealers underground and create a huge Mafia in which it is difficult for the police to remain incorruptible.
"Drug dealers and manufacturers need to be brought within the law so drugs can be controlled and licensed in the same way as alcohol and nicotine."
In 1967 Ms Coon founded RELEASE, which is a 24-hour helpline for young people with drugs problems, and has been campaigning for the legalisation of cannabis ever since.
Today's London event will be mirrored at venues around the world.
Speakers will include author of Mr Nice Guy, Howard Marks, jailed for cannabis smuggling, Joe Strummer - the former lead singer with The Clash - and comedian Mark Thomas.