Over 50 people were arrested in Hyde Park on 19 April over drugs-related offences during a "pro-cannabis" rally.
Despite police warnings that "possession of cannabis is illegal", thousands of pro-cannabis campaigners gathered at a "420 Day Celebration" at the Hyde park in support of legalizing the drug.
After several campaigners were found openly smoking the drug, 37 people were taken into custody at the Hyde Park police station and 16 others were detained elsewhere in London, reported The Evening Standard.
Meanwhile, the organiser of the rally, Stewart Harper insisted the rally was peaceful.
"We need legal access for cannabis and medical access to cannabis especially," said Harper.
"I can completely understand [worries about addiction] but if you regulated the market to make sure substances were not sold to children and that it was regulated then that is a better situation, rather than leaving it without control and to anarchy in the black market.
"We prefer to look at this as a health issue rather than a criminal issue. We are thinking of how we can reduce the harm rather than saying 'this is illegal'."
The arrests attracted criticism with a Facebook user, Phil Hicks saying: "If only they would do the same to the politicians and bankers destroying the world rather than a few smokers enjoying the world."
"If it's natural and grows in our soil can it really be that bad," said Mason Lewis Smith.