This thesis provides an examination of the social media platform Twitter and its use by private train operating companies in the United Kingdom. The relationship between the operator and its stakeholders is central to the use of Twitter by these operators. Despite Twitter being widely adopted by public transport operators, there is a lack of understanding of the motivations and uses of Twitter in the context of private train operating companies. Literature on the use of Twitter by public transport operators has focused on the functions of Twitter, content analysis of Twitter user tweets, the collection of data through Twitter, and message framing for tweets. A gap in the literature exists, however, in examining Twitter stakeholder engagement by private train operating companies, particularly from the perspectives of the operator’s staff tasked with managing their Twitter accounts. To better understand the use of Twitter by private train operators, an analysis was conducted using the theoretical framework of the social licence to operate, focusing on how Twitter is used as a stakeholder engagement tool to gain legitimacy, credibility, and trust from the operator’s stakeholders. The aim of this research was to examine the extent to which the use of Twitter by train operating companies in the United Kingdom reflects the social licence to operate. As such, this study was broken down into four objectives: 1) To analyse the Twitter accounts, tweets, and policies of train operating companies in the UK to understand the ways in which Twitter may be used as a means to obtain a social licence to operate; 2) To examine the social licence to operate in the context of UK railway regulatory requirements and Twitter use by train operating companies; 3) To explore the motivation for using Twitter through the perspectives of staff managing rail operator Twitter accounts; and 4) To explore how the COVID-19 pandemic has affected the use of train operating company Twitter use to obtain a social licence to operate. This study was conducted through an analysis of rail operator’s Twitter accounts, policies, regulations, and through a content analysis of their tweets. Semi-structured interviews with Twitter staff from franchise and open access operators were conducted to understand the motivations and policies from the perspectives of staff managing their Twitter accounts. From these objectives, four main findings emerged: 1) This study found evidence that the aspects of the social licence to operate are reflected in the use of Twitter; 2) This study shows the evolution of Twitter use from a mainly information sharing platform to one where customer service functions are offered, reflecting the finding that operators use Twitter as a tool for their customers, rather than a wider set of stakeholders; 3) The study found a lack of regulatory requirements for Twitter use and that the addition of Twitter as a committed obligation in franchise agreements, in the absence of regulations, was included as a means to set measurable requirements for operators; and 4) This study found that train operating companies used Twitter to engage with the wider community during the COVID-19 pandemic instead of only with their customers. This thesis offers recommendations for policy and practice for operators to take full advantage of Twitter’s functions in obtaining a social licence to operate. These recommendations include the establishment of regulatory guidance for Twitter use by train operating companies, a coordination of policies and practices across the rail industry, and expanding stakeholder engagement to include the community rather than focused solely on customers.