The importance of building leadership among workers is expressed by the GMB organizing principle that: ‘People are strongest when they organise themselves’. As Gall and Fiorito argue, leadership by lay members within the workplace is critical for both recruitment of new members and translating members’ commitment to the union into active participation. Recognizing organic, or natural, leaders among the workforce and integrating them into trade union structures is central to McAlevey's approach to organizing, and was a major goal for GMB organizers at BHX4.

As well as the benefits for democratic inclusion and effective organizing, building worker leadership also had important practical implications for the GMB's capacity to extend their success at BHX4 to other sites. Unionizing one site, BHX4, required a considerable concentration of the region's resources in terms of organizers’ time as well as funds. Replicating this at other sites would therefore only be possible to the extent that GMB workers at BHX4 took leadership and reduced the need for involvement of paid organizers. Developing leadership at BHX4 could also greatly accelerate unionization of other Amazon sites, through the involvement of BHX4 worker-leaders speaking to workers at the gates, with the moral authority and shared understanding that they carried as fellow Amazon workers. Whether by freeing up organizers’ time at BHX4 or travelling to other warehouses themselves, developing worker leadership was therefore critical to extending the space of organizing to other warehouses.