While secondary heads have had some of the strongest criticisms of the agreement, Mr Haggarty accepted it had brought stability to schools and the increase in salaries had attracted more entrants into teaching.
But he said there remained "unfinished business" and elements of the agreement have been subject to contradictory interpretations. The HAS has in its sights what it claims is variable funding across authorities, the "outdated" job-sizing exercise, workload pressures on senior management, the need to give chartered teachers a leadership role and the "narrow interpretation" of the 35-hour working week.
Mr Haggarty believes there remains a need to "build a culture of professional flexibility", a reference to the 35-hour week. The drive to develop strong leadership can go hand-in-hand with greater collegiality, he adds, so ensuring leadership at all levels in the system, not just in management.