LibDems want to legalise cannabis and tax air travel

They also pledged to scrap the marriage tax allowance and impose gender-neutral uniforms in schools.

Unveiling the highly controversial cannabis proposal, Lib Dem leader Jo Swinson said it would allow the sale and taxation of the drug and end possession being a criminal offence.

The party launched its manifesto outlining priorities including stopping Brexit by revoking Article 50, planting 60million trees a year, introducing free childcare from the age of nine months and ending Britain’s continuous at-sea nuclear deterrent.

At the launch in a nightclub in Camden, North London, Miss Swinson put halting Brexit at the heart of the election campaign. If the Lib Dems fail to win a majority, they would campaign for a second referendum with the option to stay in the EU.

The party also said it would allow cannabis to be sold to over-18s from licensed shops, which would raise £1.49billion a year by 2024-25. This cannabis duty would ‘break the grip’ of criminal gangs. Limits on potency levels would also be introduced.

Frequent flyers would be targeted with increases in air passenger duty, which are estimated to raise £4.86billion a year by 2024-25. These would be linked to the number of times people fly – meaning those who take an international flight once a year for a holiday would pay a lower amount than the current scheme. It will not apply to domestic flights.

Miss Swinson also pledged to scrap the marriage allowance and give more rights to co-habiting couples. The current scheme allows married couples, or those in civil partnerships, to claim up to £250 a year in income tax relief.

The party said it would recruit 20,000 new teachers and tackle climate change by generating 80 per cent of Britain’s energy through renewables by 2030.

The climate change policy includes a target of investing £15billion over five years in fitting 26million homes with insulation and zero-carbon heating.

The party also said it would provide 35 hours a week free childcare for all two to four yearolds. The Lib Dems would also give all adults £10,000 to spend on skills and training throughout their lives through the creation of a new ‘skills wallet’.

The party also vowed that mental health services would be treated with the same urgency as physical health.

Miss Swinson said: ‘This manifesto is a plan to build a brighter future for our country – and that starts with stopping Brexit.

‘Labour and the Conservatives can’t offer the country a brighter future because they both want Brexit. Our politics has been dominated by the two tired old parties for too long.’

‘20,000 new teachers’