A majority of the British public back the legalisation of cannabis so that it would be sold in shops like alcohol and tobacco, a poll has revealed.

There was also majority support for decriminalisation, something that would free up police time and resources to deal with serious crime.

The exclusive BMG Research poll for The Independent comes days after cannabis oil was for the first time brought into the UK legally, to treat an epileptic boy.

But within hours of the landmark moment, a young girl was rushed into hospital and placed on life support while she awaited a licence to get the same oil.

More than 1,500 people were asked if they supported or opposed the proposal that “cannabis be legalised, so that it is sold legally within a government regulated market in the same way that alcohol and tobacco is”.

Overall, 22 per cent strongly backed the move, while 29 per cent somewhat supported it, bringing total support to 51 per cent.

Some 19 per cent opposed the move strongly, and 16 per cent, somewhat, bringing the proportion of those against it to 35 per cent, while 14 per cent did not know.

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The respondents were then asked: “To what extent would you support or oppose cannabis be decriminalised, so that it is still a controlled substance not available for sale on the market, but that it is not criminalised (i.e. no prosecution for possession)?”

Here support rose slightly, to 52 per cent overall – with 20 per cent strongly backing it and 32 per cent somewhat behind the idea.

Some 17 per cent somewhat opposed the move, while 16 per cent strongly opposed it – total opposition of 33 per cent – and 16 per cent did not know.

High profile figures have recently backed legalisation, including former Conservative leader and foreign secretary William Hague, who said his party should be “bold” in embracing a “decisive change that would be economically and socially beneficial”.

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Durham police chief Mike Barton agreed with Lord Hague that the current system is not working and that the drug should be legalised.

He said: “The status quo is not tenable. It’s getting worse. Drugs are getting cheaper, stronger, more readily available and more dangerous.

“I have come reluctantly over the years to the conclusion that we need to regulate the market.”

Meanwhile, the charity Health Poverty Action recently estimated that legalising the drug and regulating its sale could bring in £3.5bn of tax revenue for the government every year, including extra money for the NHS.

However, a major research project that reviewed the combined results of a series of studies across Europe, recently backed previous evidence that there is a clear link between cannabis and mental health problems.

The combined results of seven studies, which looked at psychotic outcomes, found the odds of developing psychosis when a person had ever used cannabis in their life were increased by 41 per cent.

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The combined results of studies examining more frequent cannabis use showed an even greater chance of developing psychosis.

New home secretary Sajid Javid announced a review of the medicinal use of cannabis, after the mother of 12-year-old Billy Caldwell, who had cannabis oil to treat his epilepsy confiscated from her at Heathrow, demanded a change in the law.

Mr Javid told MPs: “It has become clear to me since becoming home secretary that the position we find ourselves in currently is not satisfactory. It is not satisfactory for the parent, it’s not satisfactory for the doctors and it’s not satisfactory for me.

“I’ve now come to the conclusion that it is time to review the scheduling of cannabis.”

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The commission he established has since explored evidence of the medical benefits of cannabis, with government advisors set to recommend what products might be rescheduled.

He underlined that there is no question of the government legalising cannabis for recreational use, with penalties for unauthorised supply and possession remaining in place.

Last week Hannah Deacon, a mother of another boy with epilepsy, was allowed to pass through London City Airport carrying a five-month supply of cannabis from Amsterdam.

Licences for her son Alfie Dingley to be treated were granted by the Home Office on 19 June, after a long-running battle.

But Sophia Gibson, six, from Newtownards, County Down, was rushed to hospital and placed on life support on the same day as she awaits a licence.

She suffers from a severe form of epilepsy known as Dravet syndrome. Her parents, Danielle and Darren, say the medication relieves their daughter’s condition.