Cannabis should not be prescribed for chronic pain, the NHS funding watchdog has ruled, in a decision branded ‘devastating’ by campaigners.

New guidance, released on Monday by the National Institute for Health and Care Excellence (Nice), says there is no evidence to show that cannabis is beneficial for people suffering long-term pain.

Charities had hoped that the drug would become widely available after it was decriminalised for medical use by Sajid Javid last November following high-profile campaigns involving children such as Alfie Dingley and Billy Caldwell, who both have hard-to-treat epilepsy.

But under the new ruling only people with two rare types of epilepsy, Lennox-Gastaut and Dravet syndrome, will be able to access the cannabis-derived drug Epidyolex through the NHS, meaning both Billy and Alfie will miss out.

Without Nice approval only a tiny handful of doctors are qualified and willing to prescribe medical cannabis, meaning they are virtually impossible to obtain in practice.

Millie Hinton, from the campaign End Our Pain, said the guidelines were ‘a massive missed opportunity’ for thousands of people with a range of conditions.

“It is particularly devastating that there is no positive recommendation that the NHS should allow prescribing of whole plant medical cannabis containing both CBD (cannabidiol) and THC in appropriate cases of intractable childhood epilepsy,” she said