the NHS doesn't have any controlled research on cannabis as you're not allowed to do it in the UK, so i wouldn't trust their source.
they can only go by what people have said, and as cannabis is illegal it's often sold by shady people who cut it with other things to push the weight up, the headaches could have been caused by that.
i personally haven't had a headache in months and i smoke about 2 ounces of cannabis a month.
as for the morphine point, again, you can't compare the two.
morphine is a concentrated extraction from the opiate poppy, weed is the WHOLE plant, the psychoactive component, THC, is only a fraction of the cannabinoids in marijuana.
you can grow AS MANY opiate poppies as you like in the UK, as soon as you germinate a seed of cannabis, you risk prison time.









But something about businesses collapsing, people losing jobs and the economy being destroyed or something like that 


