Predetermination is not allowed under the Code of Conduct that all Councillors have to sign when they take office. There is a requirement for councillors to come to meetings prepared and, perhaps with a solution in mind but they must engage in a debate at the meeting and agree to a resolution from that debate.
Decisions are collective-based and not made by individuals. However in reality, agenda items are often discussed in advance and if councillors share a political persuasion, then they may consensus on the answer. It is up to the remaining councillors, if they oppose the decision to debate strongly and convince their peers.
However, to come to a meeting and say 'this is what has been decided' is wrong and against the 7 principles of public office which are namely selflessness, integrity, objectivity, accountability, openness, honesty and leadership