The court's decision usually seems to be summarised as "A council cannot lawfully decide any matter which is not specified in the summons".
Or putting it in the negative, any decision made without a clear agenda item is unlawful.
The full judgement included:
"It may be that a very important question is going to be considered at the meeting; it may be on the other hand that the only business is purely formal, paying some tradesman or something of that description. In the one case the members would attend in force and in the other case it was a mere matter of form, the members would not attend beyond the necessary quorum. Accordingly, the notice convening the meeting should contain sufficient description of the important business which the meeting is to transact, and the meeting cannot in ordinary circumstances go outside the business mentioned in that notice"
(The summons is the injunction on councillors to attend the meeting, followed by the agenda for the meeting. It's called a summons rather than an invitation or similar because councillors have a duty to try to attend council meetings).
Another decision was R v The corporation of Dublin (1911) where a special meeting of the corporation was summoned on a requisition of seven ratepayers to consider the question of unemployment in the city and ways and means of alleviating it. At the meeting a resolution was passed authorising the city treasurer to arrange payment of £10,000 on useful works for the alleviation of unemployment. It was held that the notice of the meeting was insufficient to enable the meeting to pass such a resolution. This case gives an indication of how the agenda needs to give a clear and reasonably precise indication of what is to be considered.
Although these judgements refer primarily to informing councillors about matters to be considered, I would regard it as equally important that the public should be informed in advance of the meeting, so that they have the opportunity to express their views to councillors.
