LIBDEM leader Tim Farron launched his party’s manifesto yesterday with a call to legalise cannabis, in what the party claim could be £1 billion money spinner for the tax man.

The radical reform of Britain’s drug laws was one of the key pledges in the document that the LibDems say they started working on in preparation for a snap election when Theresa May became Prime Minister last year.

But as with the much of the General Election campaign so far, it’s the constitution that dominates the party’s 100-page offer to voters, launched in London yesterday.

In the document, Farron commits his party to a second referendum on the UK’s membership of the European Union but also restates his party’s opposition to a second Scottish independence referendum. Instead, he promises Scotland home rule and access to both the single market of the EU and the UK.

There was a pledge to ban diesel cars, and another to introduce a rent-to-buy scheme to help tenants pay towards owning their home over a 30-year-period, The LibDems also say they will restore housing benefit to young people, bring in bus passes for 16 to 21-year-olds, and lower the voting age to 16.

Farron said: “You don’t have to accept Theresa May and Nigel Farage’s extreme version of Brexit that will wreck the future for you, your family, your schools and hospitals.

“In the biggest fight for the future of our country in a generation, Jeremy Corbyn’s Labour has let you down by voting with Theresa May on Brexit, not against her. The Liberal Democrats want you to have a choice over your future.

“You should have your say on the Brexit deal in a referendum. And if you don’t like the deal you should be able to reject it and choose to remain in Europe.

“We want to give all our children a brighter future in a fairer Britain where people are decent to each other, with good schools and hospitals, a clean environment and an innovative economy.

“Not Theresa May’s cold, mean-spirited Britain.”

In the manifesto, the LibDem proposals for a “regulated market for cannabis” would “break the grip of the criminal gangs and protect young people,” the party said, describing the government’s current prohibition policy as a “catastrophic failure.”

“Every year, billions flow to organised crime while we needlessly prosecute and imprison thousands of people, blighting their employment and life chances, and doing nothing to address the impact of drugs on their health. Our current approach to drugs helps nobody except criminal gangs.”

A Treasury’s report, commissioned by Nick Clegg before the 2015 election when he was still Deputy Prime Minister suggested annual government benefits would be between £750m and £1.05bn.

Under Lib Dems plans, specialist shops with appropriate licenses would be able sell cannabis,and users could also grow their own at home.

The manifesto policy would base the duty charged on the drug on the potency of the product sold.

The Lib Dems have also pledged to replace imprisonment for possession of illegal drugs with civil penalties and to repeal the Psychoactive Substances Act, the so-called legal high ban, which they claim pushed the market underground making it much more dangerous.

Paul Johnson, director of economic think tank the Institute for Fiscal Studies, told BBC Radio 4’s World at One: “The costings look like they add up in the sense that there are a set of numbers for tax increases they propose, all of which are much more modest than what we saw yesterday [from Labour].

“The £6 billion from income tax is pretty certain because it’s a small increase on an awful lot of people.”

The SNP’s John Nicolson said history showed the Lib Dems couldn’t be trusted to “stand up to the Tories”.

“Scotland has not forgotten the Lib Dem record of betrayal propping up the Tories in government.

“For five years they rubber-stamped Tory austerity – cutting £2.3billion from Scotland’s budget for public services, they trebled university tuition fees despite promising to abolish them, they scrapped the Education Maintenance Allowance, introduced the bedroom tax, cut disability benefits, and backed Tory changes to the State Pension that deny millions of women the pension they deserve.”

“With the Lib Dems now preparing to prop the Tories up again in local councils across Scotland – it is no wonder that former members and supporters are turning to the SNP in droves to stand up for Scotland and provide the strong opposition needed to Tory cuts and a hard Brexit.

“A vote for the SNP on June 8th is a vote to stand stronger for Scotland – we will continue working hard to make the Scotland the best country it can be.”