Former Conservative leader Lord Hague has called for "a major change in policy" on cannabis, saying the Government should consider following Canada's approach and legalise it for recreational use.

Lord Hague, writing in the Daily Telegraph, said that any "war" on cannabis has been "comprehensively and irreversibly lost" and the idea the drugs can be driven off the street by the state "is nothing short of deluded".

His intervention comes after a raft of MPs called for reform to the law.

On Monday, Health Secretary Jeremy Hunt told ITV News that he backs the use of medicinal cannabis oil.

The calls for change have grown in recent days following widespread outrage over the confiscation from mother Charlotte Caldwell of cannabis oil supplies which she brought from Canada for her 12-year-old son Billy, who has acute epilepsy.

After Billy was rushed to hospital on Friday night in a critical condition having suffered multiple seizures, Home Secretary Sajid Javid granted a 20-day emergency licence granting use of the oil. He has now been discharged from hospital.

The Government announced a new expert panel of clinicians would be established to give swift advice on the prescription of cannabis-based medicines to individual patients.

But Prime Minister Theresa May suggested the Government would look only into the operation of the current system of licences for use in individual cases, rather than reviewing the law more widely.

The Home Office said the Government had no intention of reviewing the drug's classification.

Lord Hague, who led the party from 1997 to 2001 and was foreign secretary under David Cameron from 2010 to 2014, said the fact that the Home Office returned Billy's medicine meant they had "conceded that the law has become indefensible".

"It should now be asked whether Britain should join the many other countries that permit medical-grade marijuana, or indeed join Canada in preparing for a lawful, regulated market in cannabis for recreational use as well," he wrote in the paper.

He added: "Everyone sitting in a Whitehall conference room needs to recognise that, out there, cannabis is ubiquitous, and issuing orders to the police to defeat its use is about as up-to-date and relevant as asking the Army to recover the Empire.

"This battle is effectively over."

Ms Caldwell, 50, from Co Tyrone, wants an urgent review of the law on the substance, which is banned in the UK despite being available in many other countries.

She credits cannabis oil with keeping the boy's seizures at bay, saying he was seizure-free for more than 300 days while using it, but THC is restricted in the UK.

She demanded a meeting with the Home Secretary and the Health Secretary "within 24 hours".

Speaking outside hospital, she said: "The fact that Billy has been discharged is testimony to the effectiveness of the treatment and underlines how vital it is that every child and every single family affected in our country should have immediate access to the very same medication."

Shadow home secretary Diane Abbott said Labour supports the legal prescription of cannabis oil for medical purposes, saying: "Children have been put at risk and experienced extraordinary suffering because this Government drags its heels and refuses to grant cannabis oil licences."

A spokeswoman for the Home Office said: "There is strong scientific and medical evidence that cannabis is a harmful drug which can harm people's mental and physical health and can damage communities. The Government is clear - we must prevent drug use in our communities and help those dependent on drugs to recover, while ensuring our drugs laws are enforced.

"The Government has no intention of reviewing the classification of cannabis and it will remain a class B drug. Classification is completely separate to scheduling regulations.

"Any debate within government about the efficacy and therapeutic use of cannabis-based medicines emphatically does not extend to any review regarding the classification of cannabis and the penalties for the illicit possession, cultivation and trafficking of cannabis will remain the same."