In their role as first responders, police services in England provide immediate assistance to individuals at a scene of emergency and/or potential criminal event. However, the significant reduction in policing resources since 2010 has demanded officers to work more broadly in response to the diverse range of incidents. Therefore, training needs and settings must be not only varied, but efficient as well as effective. Extended Reality (XR), including both virtual and augmented reality, is becoming prominent in many sectors for training and operations. Yet, in the rush to exploit the benefits of XR for immersive training, the potential digital vulnerabilities that may be exposed have yet to be properly examined. RespondXR will consequently, for the first time, map the vulnerability space (i.e., its social, technical, legal, ethical risks and impacts), from the perspective of (a) those delivering the training, (b) the first responders who will be undertaking this training, and (c) the technical teams bringing forward new training methodologies in XR. The project will explore the socio-technical challenges posed by the adoption of this technology, providing the foundations for further research on the safe, secure, and ethical use of immersive training technology for enhancing the response of policing in England.