Thanks for that.
From your first link, this seems to be the key:Responsibility for the recruitment of new trustees rests firmly with the existing trustees. They must oversee the management of an open and efficient process and always act in the best interests of the charity.
Members don't really enter into it.
It's not quite that they don't enter into it, but it's pretty obvious that the Charity Commission is not very interested in their role. The second link focuses largely on the perceived problems of having voting members in your charity, though it does mention some of the advantages. The CC doesn't seem very bothered about "democracy" in charities generally. Its overriding concern is that the charity is run efficiently and legally and uses its resources to advance its stated charitable objectives.
But yes, in short, Charity Commission guidance indicates that the buck stops with the existing trustees when it comes to choosing new trustees. This does clash a bit with company law, in which the members of the company have the final say about who's on the board. It's one of the many interesting features of having a company that's also a charity.