And thirdly:

I've also now read 'Your Thyroid and How to Keep It Healthy', by Barry Durrant-Peatfield, who appears to have been a proper doctor who had the disease and tried the obvious things and was converted.

There are a couple of mistakes, to my mind, in the book, but it's basically sound from my point of view if taken as the honest report/advice of a brave man rather than as the whole truth. In fact given that he 'voluntarily erased himself from the medical register' and went into retirement, I'd be tempted to call him either a martyr or someone who didn't think he could back up his beliefs in star-chamber.

You might well think him a quack who was damaging people. I now strongly suspect that he was failing in his professional duty to ignore the evidence of his own eyes, and to not do the things he thought helped.

He does seem quite concerned about fluoride and mercury fillings. I haven't looked into those. Yet. Sigh. And he talks about adrenal problems a lot. I don't know what I think about that. Certainly I wouldn't be at all surprised to find out that it was possible to have a 'peripheral resistance to adrenal hormones'.