Cannabis plants spotted near Tower of London
Cannabis plants spotted near Tower of LondonFinn Hemingway

Cannabis plants aren't what you expect to see as you take in the sights of central London - but now pedestrians strolling around the South Bank and the Tower of London are getting a close-up of the distinctive herbs.

Campaigners have taken the radical step to scatter cannabis or hemp seeds across the UK to persuade the government to decriminalise the Class B drug for medicinal and recreational purposes.

Under the guise of "feeding the birds", the campaign is completely legal and has soared in popularity with more than 2,000 people - aged between 18 to 30 - joining the cause.

Finn Hemingway, who founded the #Feed420 campaign, said 50 plants were growing along the South Bank and 30 near the Tower of London.

"I can't believe how popular the campaign has become. If there are politicians who want to get in contact instead of sitting back we would be more than happy to get things moving," he told IBTimes UK.

Cannabis plants in London
Cannabis plants in LondonFinn Hemingway

A spokesperson for the Home Office confirmed the campaigners were not breaking the law on the condition they were not cultivating the plants.

Hemingway believes it should become a political issue after academics from the University of Essex proved billions could be generated through tax revenue if cannabis was properly regulated.

The 2013 study, led by economics professor Stephen Pudney, found that England and Wales could also save up to £300m per year on policing, prosecuting, and treatment if marijuana were decriminalised.

"In the first year of regulation we could generate £7 billion out of tax. I think that's seven billion reasons to take it more seriously. The only dangerous thing about cannabis is you can be arrested, " he said.

"It's criminal locking up people who need to use it."

Hemingway said the onset of psychosis was now largely attributed to the consumption of alcohol rather than cannabis.

He also said it is currently hard for cancer patients or multiple sclerosis sufferers to get hold of any prescriptive drugs such as Sativex - a cannabinoid medicine - to alleviate their pain.

"Friends and family have tried to get prescriptive drugs but doctors prohibit giving them out. But clearly, it's available over the prescription counter."

He added that, ideally, he would like people to be able to independently grow seeds one day away from the black market.

Cannabis plants spotted in London
Cannabis plants spotted in LondonFinn Hemingway