* Your tone is important. A confrontational or legalistic approach is doomed from the start. The watchwords are sweet reason and enough political finesse to convince the leadership that any new approach was all their idea.
* Set an example by routinely working hard until 5pm, with no break for chat or a breather, and then leaving - conscience-free - for home. Those with families and outside interests will be pleased to see it become accepted practice. If they go along with you, the head will get the message.
* For every meeting, ask for a detailed agenda in advance. If there isn't one, question the need for the meeting. If, when you read the agenda, you think you needn't be there, say so. If the agenda item you're concerned with is finished, excuse yourself and go home or back to your work if it's early.
* Ask for a review of the parent evening programme that balances their benefits against the effort expended. Suggest they're seen in the context of the whole-school policy of written reports and individual access to teachers.
* Draw the attention of the leadership to individuals who seem to be carrying more than their share of extra duties - PE or music teachers, perhaps. What support can be given either financially or through the timetable?