Most councils operate a Cabinet system. The councillors who are Cabinet members have long briefing meeting with council officers in private to discuss what decisions to take. Then the formal Cabinet meetings are in public. These offer a chance for the public and opposition councillors to challenge proposals, or raise points of detail, before final decisions are taken.
Some parts of these meetings are held in private when there are items of commercial sensitivity being discussed - for instance awarding contracts. The usual form here is that the press and public are excluded for these items, but that opposition councillors are able to attend.
However at Cumbria County Council, now Labour led, the Conservative opposition councillors have been excluded from an item concerning a new council headquarters.