I think you're saying that an informal compromise is not possible in this instance, and that it's a matter simply - that the process must be adhered to. Well, that does take us forward, in an understanding of what to do next, at least.
However, still can't find anything in the council's code of conduct or in the Nolan Principles about whether councillors can discuss - outside the meeting - a potential candidate's qualities. (The Nolan Principles, as I read them, refer only to decisons, and the way the decisions were arrived at, which must be openly presented to the public at meetings. As I understand it, councillors can discuss issues, in the pub say, with other cllrs or members of the public, so long as they come to meetings with open minds and also ready to explain their thinking behind any decision).
It's obviously a dense area! It may be something we need to address in any revision of the council's code of conduct.
Thanks for this exchange, and thanks for your time. I have learned a lot!