I've been reading comments on here and elsewhere with the same sense of frustration as some others at the lack of understanding of mitochondrial disease, and the way that this lack of understanding doesn't stop people expressing strong opinions that must be devastating for parents (is devastating actually) who have lost children to mitochondrial disease to read.
I'd like to give huge 
to all those who have shared their stories of losing children on here.
My two nephews died of mitochondrial disease, the second five years ago now. They had a variant that only four people in the world have been diagnosed with. It really matters when talking about treatment - these tiny variations make a big difference in how children respond to things because their genes are doing different things.
Mitochondrial encephalopathy is progressive, and incurable. This experimental treatment appears to be looking to halt progression in the variants that are responsive to it. It won't reverse existing damage because those cells are now gone. They burn out and can't be replaced.
In some cases degeneration happens gradually and in others dramatically. Overnight a function (e.g. Swallowing, digesting, muscle power) is lost. Sometimes, as with types of MS, the function is partially regained in time but some essential loss remains, and will worsen the next time. In other types the damage is serious and permanent.
The field of mitochondrial disease is still relatively small as it only began to be understood very well in the 1980s; it remains under diagnosed now. Five years ago the U.K. only had four mito research centres (that may have increased since) but they contained world experts. I can guess at the identity of those treating Charlie and the expert witness in Newcastle because the field is so small, but they are so bloody good.
The lives of both my nephews were made unbearable by this vile, untreatable disease. One died as a baby, after my brother and wife were advised to have ventilator support removed because the part of his brain that supported breathing was no longer working. He died an hour after the ventilator was turned off. You can imagine how they are finding the current coverage. They trusted their medical team completely and were advised that life on the ventilator was distressing for their son, that he might be in pain, and that he would be very likely to die of opportunistic infection in any case.
My other nephew was older. In him, we saw the loss of our healthy boy as he lost the ability to see, walk, swallow, think, his continence and had constant seizures. His end of life care was in a hospice and his plan stated no medical intervention other than measures to keep him comfortable. The only treatment his world class clinician could offer was vitamins and amino acids because that's all there is.
Charlie won't get better. In the very unlikely event he responds to treatment that has never been tried on his illness before, he would stay as he is, perhaps very, very slightly improved.
We raise funds for mitochondrial research and are part of two very supportive and knowlegeable parent support groups who remain connected to research and medical staff. If this treatment was offering miracles, we would know.
My heart breaks for Charlie's parents but this case is hideous, and must be destroying the HCPs too. I hope for everyone's sake that Charlie is allowed to be at peace soon.