I had been thinking back recently about the whole NHS consultant situation. From my own experience with a family member, boundaries can become blurred when you have the same consultant for a number of years and also live in a relatively small rural community. An element of mutual trust, friendship and familiarity can develop in appointments over time. You might see each other out and about in the local area, you might have mutual friends or interests and your children might attend the same schools. When the patient is also a person in the public eye, that can be of interest to the consultant, be an equaliser in status and give the consultant some kudos - and something to talk gossip about - with colleagues. After the professional relationship has ended, a real friendship might develop out in the real world.
The trust a consultant has in a patient is particularly important when at least some self-reporting of symptoms and severity has to be replied upon.
A consultant knowingly reviewing a book by a patient's spouse - a spouse who also attends appointments - could be seen as a conflict of interest; as crossing professional boundaries.
To be clear, I don't know if the consultants in the letters released by the Walker-Winn-Wyns are the same person, nor if the consultant who reviewed TSP is Timmoth's consultant. I am not accusing the consultant/s of anything improper, just thinking possibilities through from my own experience.