Medical cannabis oil has been returned to a child with a severe case of epilepsy after being confiscated from his mother at customs.

Billy Caldwell , 12, was given the oil after doctors said it was a “medical emergency”, Sajid Javid said.

Billy's mother, Charlotte Caldwell, from County Tyrone, said they had “achieved the impossible” but called for the oil to be freely available.

Billy started using cannabis oil in 2016 to control his seizures.

Cannabis oil, which contains a substance called Tetrahydrocannabinol (THC), is illegal in England, but available in other places.

Billy’s most recent stash – which Ms Caldwell had tried to bring into the UK from Canada – was confiscated at Heathrow Airport on June 12, and he was admitted to hospital before Mr Javid said it would be returned.

The oil arrived at Chelsea and Westminster Hospital, where Billy is being treated, on the afternoon of June 16. He has been given a 20-day special leave and is not allowed to take it home.

A Home Office spokeswoman said it was an “exceptional leave” for a “short-term emergency”, and would need to be reviewed.

'Completely destroyed'

Ms Caldwell said: “I really believe that somewhere in the Home Office there is someone with a heart, and I really believe Billy has touched that person deeply.”

But he said [Billy's] “little body and mind were completely destroyed.”

“No other family should have to go through this ordeal, traveling halfway around the world to get medicine that should be freely available,” she said.

“My experience leaves me in no doubt that the Home Office can no longer play a role in the administration of medicines for sick children in our country.

“Children are dying, and this must be stopped immediately.”

Mr Javid said he had issued a licence to allow Billy to be treated with cannabis oil after several discussions with the boy's medical team.

“This is a very complicated situation, but our immediate priority is to make sure Billy receives the most effective treatment possible in a safe manner,” she said.

“My decision is based on the advice of expert clinicians who have made it clear that this is a medical emergency.

“The security minister met with the family on Monday, and has since then been working to reach an urgent solution.”

Barbara Zieniewicz, co-founder of the advocacy group Families4Access, who traveled to Canada with Billy and Ms Caldwell, called Mr Javid’s decision “triumphant”.

“I truly believe that this is the first push – from here, it’s a chain reaction. This, to me, means that there is hope, not just for Billy, but for all the families who need it.”

Billy, from Castlederg, began treatment in 2016 in America, where medical marijuana is legal.

Ms. Caldwell says Billy's seizures decrease dramatically when he takes the oil.

In 2017, he was prescribed the medicine by the NHS. But in May this year, his GP was told he could no longer prescribe it.

At the time the Department of Health in Northern Ireland said that cannabis had not yet been approved as a medicine in the UK.

In June, Ms Caldwell attempted to smuggle a six-month supply of the oil – to treat up to 100 seizures a day – into Britain from Toronto, but the substance was confiscated by officials at Heathrow Airport.

The boy's family said he was taken to the hospital when the seizures intensified in the following days.

The family's deputy, Órfhlaith Begley, said the Home Office's decision was “life-saving”, adding: “I will continue to challenge the Home Office and the health authorities to ensure he has long-term access to his medication so there is no repeat of the trauma he has suffered in recent weeks.”

'Not simple'

Dr Amir Englund, who studies cannabis at the Institute of Psychiatry, King's College London, said: “Clearly, there is evidence that Billy's medications are working for him where others have failed.

“The government’s job is to protect its citizens from harm by regulating medicines so that the ones doctors prescribe are safe and effective.

“However, there are cases where these measures become counterproductive and harmful. This is an example of that, and the Home Office should allow an exemption so that further harm is not done to them.”

Meanwhile, University College London clinical lecturer in psychiatry, Dr Michael Bloomfield, said that on the one hand “the current laws are too harsh”, but added that the medical marijuana issue was “far from simple”.

“Any 'medical marijuana' requires a scientific basis of evidence, in the form of medical trials etc., which is lacking for many disorders, and has become, for many jurisdictions, a potential way to decriminalize cannabis by backdoors,” he said.

Does Cannabis Have Medicinal Benefits?

CBD and Tetrahydrocannabinol (THC) are two types of cannabinoids that occur naturally in the resin of marijuana plants.

A cannabis-based drug, Sativex, has been approved in England to treat multiple sclerosis. It contains THC and CBD.

Doctors could, in theory, prescribe it for other things outside of the license, but at their own risk.

Multiple sclerosis patients who have been prescribed Sativex and who buy it for other people are subject to criminal prosecution.

Another approved treatment is Nabilone. It contains a man-made version of THC and can be given to cancer patients to help relieve nausea during chemotherapy.