Much has been written about Lean, Agile and Just-in-Time philosophies and how these approaches will improve the efficiency and flow of a product through a supply chain. The UK automotive supply industry is in the main stream using these principles to achieve very demanding requirements from customers for sequential and synchronous delivery of final assembly and component parts. This thesis provides the reader with case study research that identifies the further potential for synchronous supply in the UK automotive industry supply network. Consideration has been made to the effect of synchronous supply beyond the vehicle manufacturer's assembly hall to improve efficiency and effectiveness within the network. The clear position for Tier 0.5 module suppliers and Tier 0 'in-source' suppliers to a vehicle manufacturer was also uniquely identified as actual working practice within the network. The method used was a case study approach using qualitative methods of interview and observation at nine automotive supply chain organisations, eight of which were operating in an actual UK automotive supply network. This followed an initial study used to clarify the thesis research position. Semi-structured interviews were used for the case studies to gain initial empirical research for this thesis and concluded that further empirical research was required in order to determine if synchronous supply would benefit a wider selection of networked suppliers. The main study, in two parts, provided the in-depth case study detail related back through benchmark tables to the literature review to identify the true position for in-sourcing the supplier and the Tier 0 supplier position. Findings confirm the above and state the position for 'Triangles of efficiency' between close knit tiers of the UK automotive supply network. In-source supplier assembly was uniquely identified within this thesis and seen as an opportunity for both the VM and leading suppliers to improve and enhance both their synchronous efficiencies; the VM, by allocating an assembly area to suppliers within their facilities to reduce delivery time and make the assembly process of modules more visible in the supply network; the supplier, by offering a leading Tier 0 position ahead of the business park Tier 0.5 status more commonly understood in automotive supplier networks.