The paper explores defining legitimacy in the context of the complexities of decision-making in the English planning system, reviewing existing literature on the influences and implications of politics of planning, existing and future monitoring of decision-making as well as examining the relationship between officers and local politicians (members). It is evident from the available literature that few studies have been undertaken in assessing the legitimacy of decision-making of Development Control Committees (DCC) and it is this paucity of information which the research hopes to contribute to. In assessing the legitimacy of decision-making at DCC, a methodology is formulated to determine the legitimacy of decision-making at Local Planning Authorities (LPAs) in Essex, utilising application and appeal outcomes. The broad findings of the aggregate data analyses inter alia demonstrate that members are less likely to make legitimate decisions. In depth case-study analyses carried out for six LPAs provides an increased understanding of the findings, highlighting the implications of the perceived lack of transparency, probity and trust, and the potential impacts on first and third parties involved in the planning system. Potential solutions to resolve the implications of the trends observed in data are offered through improving member-officer relationships, improving member and officer training as well the merits of implementing a third-party right of appeal (TPRA) to secure/restore transparency, probity and trust in the planning system, ultimately improving the legitimacy of decision-making.