Paul Flynn, Labour MP for Newport West, to lead debate on 12 October, though campaigners not hopeful that law will be changed as a result

MPs will debate whether to legalise the production, sale and use of cannabis after a petition calling for a change in the law reached more than 200,000 signatures.

Paul Flynn, Labour MP for Newport West, who has worked with cannabis law reform campaigners, will lead the debate in Westminster Hall on 12 October.

The government has already insisted in reply that it has no plans to legalise cannabis since a change in the law “would not address the harm to individuals and communities”.

James Owen, who started the petition, said that despite public backing – it reached more than 125,000 signatures in just five days after it was posted in August – he was not hopeful that the debate could change the government’s position.

“I’m glad that it’s got this far and can just take its process,” the 25-year-old economics student said. “I’d be more hopeful if Jeremy Corbyn gets the leadership of the Labour party, but it seems to me that the current government are willing to ignore the views of 200,000-plus people.”

Nevertheless, Owen said he would try to make it to London to watch the debate, university timetable permitting.

Flynn has campaigned for cannabis reform for more than 25 years. Four years ago, he sponsored the launch in parliament of the report How to Regulate Cannabis in Britain, drafted by Clear UK, Britain’s biggest pro-reform group.

Peter Reynolds, leader of Clear, backed Flynn’s involvement in the debate, calling him a “great bloke”.

“He’s a man of tremendous integrity and I think he has a great deal of respect in the house, although some regard him as a bit of an eccentric,” Reynolds said.

“I’ve been frustrated by Paul’s tactics in the past, because he’s said to me we need to move slowly to a position of consensus but I think we’ve allowed the people who oppose us to get away with far too much over the past few years. But Paul’s probably the only choice for the debate.”

Reynolds was under no illusions as to the debate’s probable outcome, speculating that government whips would probably pressure Conservative MPs to not even attend. But he remained hopeful and has called on Clear members to lobby their MPs.

“It’s a war of attrition. The strength of our case is inarguable, our arguments are irrefutable and they are being acted on and proven throughout the world. No matter how reticent and reactionary the UK government are we will grind them down,” he said.

With its date now set and as called for, the cannabis petition has become the most successful of all recent petitions on parliament’s official e-petitions website, although it is far from the most signed. A second petition of more than 100,000 signatures, which had called for a debate on a vote of no confidence in Jeremy Hunt, the health secretary, was accepted but only as a debate on “the e-petition relating to contracts and conditions in the NHS”.

However, another petition calling on the government to accept more asylum seekers and increase support for refugee migrants to Britain, which gained over 430,000 signatures, the most ever on the site, was dismissed. MPs on the petitions committee decided that the Commons had already had opportunities to consider the issue.

Katie Whyte, who started that petition, said she was frustrated by the decision. “Everyone was hoping for more than that,” she said. “It was an opportunity for some more focus and I think people have higher expectations. I think there is going to be more pressure on the government. I know there is a protest on Saturday.

“People are coming together here and attitudes are changing. British people want to do more and we are only able to do that if the government supports us.”

