April 20 sees users of the plant in its varying forms gather to celebrate its consumption and advocate decriminalisation of the drug.
In Hyde Park, hundreds of people could be seen basking in the sun while some were smoking the substance in public.
While listening to music and enjoying the festival atmosphere were clear motivators, many attendees wanted to advocate an open discourse around cannabis use.
“It’s an opportunity to talk to people who are interested in cannabis,” said Barny de Hoedt, the editor of a magazine about cannabis culture called Quarter Leaf.
“It gives a chance to connect with people.”
He spoke of their being medicinal uses of cannabis and his desire to see its use legalised.
Others spoke of the other uses of the cannabis plant, such as the product hemp, which can then be used to create other items.
Adam Ohman, a hemp producer, described how that could be used to produce sustainable clothing and household items.
He spoke of the “positive uses” of the item.
In regards to cannabis, he called for “decriminalisation with some form of regulation”.
“I want to see more of an acceptance,” he said in regards to its use, stating his opinion that recreational users should not have their lives ruined for doing so.
Others spoke of the “friendly” atmosphere in the park and seemed mostly determined to enjoy the day in the sun.
Jonathan, who declined to give his last name, said: “I usually come here most years.
“It brings people out, all walks and ages and backgrounds coming together.
“Most of the time it’s pretty chill.”
Another attendee, Will Yoxall, told the Standard: “It’s been really good, really friendly.”
Police had put up signs stating the use of cannabis was illegal in the park and patrolled the area.
The grounds were set to be cleared of those involved in 420 at 5pm.
It has been suggested that the number 420 came from the penal code the Californian police used to categorise cannabis cases.
Students at a Californian high school allegedly organised a meeting at 4.20pm to find a plot of land to plant a cannabis plant in 1971.
Rallies and celebrations of weed were taking place across the world on Saturday, stretching as far as New Zealand and America.
Cannabis users can go to jail if caught.
However, traffickers and dealers are more likely to receive prison sentences.