We don't need to worry about all of that now - that's for the lawyers to argue about. And apparently there is a law firm which is willing to take on a lawsuit involving medical negligence related to ME and are looking for clients. I'm wondering if they're thinking of a class action, or individual plaintiffs.
I think the simple question is if you believe you are a victim of medical negligence related to ME in the UK, and are interested in pursuing a legal remedy, then contact the law firm named above. It looks like a contingency fee case - "no win/no fee" - if they're successful, they would get a percentage of any settlement or damages paid. And it would be up to the lawyers to prove their case, or not - but it wouldn't cost you anything to try.
Although I do have a question about costs involved - depositions etc - I'd want to know how those get paid if they lose the case.
Who knows - if by some miracle they were successful, it might light a fire under the medical establishment to try to avoid getting sued again - i.e., to actually learn about ME.