Role of collaboration in green supply chains in the UK: An exploratory study on suppliers, logistics and retailers perspectivesMany companies around the world have started to realise that working alone will not be sufficient in their move towards a greener supply chain (SC). More specifically, recent UK government regulations on implementing strict CO2 reduction encourage SC operators to work collaboratively, in production and logistics or other operations, to achieve their green objectives. In this research, we look at some underlying factors of SC collaboration, focussing on suppliers, logistics and retailers, for the purpose of improving the environmental sustainability of companies' SCs. To facilitate our study, we conduct case studies in two overseas supplier companies with the aim of providing a better understanding of how green issues imposed by European and UK customers influence the companies' actions to meet agreed environmental goals. Based on the initial analysis of the case studies, we develop a conceptual framework which indicates that SC collaboration plays an important role in ensuring companies achieve environmental sustainability of their SCs. Subsequently, staff in middle-management and related roles in sixteen companies operating in the UK are interviewed. This allows us to understand their business practices in terms of SC collaboration with their suppliers and buyers to achieve the goal of CO2 reduction. Finally, drawing upon the information from company reports and websites, a number of UK leading retailers' actions to reduce CO2 emissions are investigated. We develop a conceptual framework of SC collaboration for environmental sustainability to help companies improve their level of collaboration between suppliers and buyers in terms of meeting their environmental objectives. The proposed framework will serve as a base model for the companies using or considering SC collaboration to achieve their environmental agendas, in line with governmental green regulatory requirements.