I think Harry might come to regret that title because it suggests that the publishers might be positioning the book as both a sympathetic treatment of his point of view, but also a study of somebody who is bitter at being second best, who is not quite the star they want to be.
The title is accurate: that's what royals and big landowners did - gave a 'spare' to inherit, but it also conjures undertones of the understudy. It had that sad connotation of: 'also run'; ' always the bridesmaid'; second best. If the book was titled
'on the bench' (as in footballing parlance) , it wouldn't have a very positive vibe about the subject's capabilities, and I wonder if this is a sort of undertone that the publishers are allowing. Perhaps the book is going to be subjective in what it reveals, but there is going to be an objective slant of 'this is what a bitter person who is in the shadow comes across as.'
Harry wrote earlier that this wouldn't be the book of the man whom he was born, but one of the man he has become. It looks like the publishers have junked that idea and put across that he isn't interesting enough as the man he has become: the public want the juicy royal details.
I hope that Harry doesn't come to regret this enterprise and feel that it dogs him with the impression that he is a jealous also ran, who had it all and somehow wanted the bigger role. That story that he wants to make a mark and fears his nephew will take his place at the age of 18, might not be true, but fits the whole idea of wanting to be an important Royal. He has got to escape that mantle, for his own peace of mind.
It's a shame, because, for many years, he was known for his personality and sense of fun and what seemed like his warmth. He was very popular and had something unique about him. I don't think he needed to be in anybody's shadow, as a person. The Invictus Games seemed like a spontaneous, really warm and human initiative, and the way he pushed it forward seemed heartfelt and genuine. I think he was using his royal profile to do a few really worthwhile things, which he could do well. That was enough: raising the profile of injured military veterans. He knew how to focus on certain needed projects.- a bit like the Prince of Wales's trust, or the Duke of Edinburgh awards. On occasions, I bet a young William had been envious of his brother's popular personality.
It is a shame that he has chosen to bite the hand that fed him, a hand that was always ready to praise and pat on the head, when he wasn't behaving very dutifully. I'm sure references to 'the spare' were said ironically in upper class circles. You'd have to have no sense of irony to see it otherwise. But, it's really time for him to be his own person and escape the royal trappings and to stop being manipulated by publishers and publicists who are only interested in what juicy titbits he can tell about being a royal from an inside view.