The Major Projects Agreement (MPA) is a framework collective agreement designed to enhance performance outcomes in large mechanical and electrical engineering projects. It includes the trade union as a partner in strategic, organisational and employment decisions. The agreement was recently implemented in the construction of Heathrow Terminal 5 (T5). We look at factors in the corporate governance and industrial relations environment that led to the use of the MPA at T5 and assess its contribution to the completion of the construction project there. That the MPA has not been more widely adopted since the completion of T5 is indicative, we suggest, of institutional constraints on labour-management partnerships in Britain. © 2009 Industrial Law Society; all rights reserved.