Role: Operational Acceptance Test Engineer Hybrid: Predominantly work from home - on-site in Croydon/M3 Corridor when required. Start Date: May Due to nature of this role, we require the successful candidate to be able to obtain high level security clearance. You must have lived permanently in the UK for the last 5 years to be eligible. You must also hold a British Passport only. Job Overview: We are seeking a highly skilled Operational Acceptance Test (OAT) Engineer to oversee and lead the end-to-end operational testing process. The ideal candidate will have a strong background in operational readiness, system performance and production environment validation on cloud-based services. Key Responsibilities: Act as a senior member of the team, taking lead on Operational Acceptance Testing (OAT) process, ensuring systems meet operational and business requirements before deployment. Define OAT test strategies, plans and criteria to validate infrastructure, system reliability, failover mechanisms and non-functional requirements. Collaborate with DevOps, Infrastructure and Release Management teams to ensure smooth transition from development to production on AWS cloud. Conduct cloud-based resilience, failover, backup and recovery testing. Ensure compliance with SLAs, security policies and disaster recovery procedures. Identify, document, and manage defects and issues, ensuring timely resolution. Provide leadership and mentoring to junior testers and team members. Generate detailed reports and dashboards on OAT progress, results, and risk assessments. Required Skills & Experience: Experienced in Operational Testing. Deep understanding of OAT methodologies, including but not limited to the following core areas: Build verification Alert and Monitoring Backup and Restore Resilience and Recovery Logging, Audit and House Keeping Release Management Config Management Work Instructions OWASP "top ten" security tests Experience with CI/CD pipelines, Jenkins, and test automation frameworks. Knowledge of cloud platforms (AWS/Azure), infrastructure monitoring, and IT service management. Familiarity with databases, Linux environments, and network protocols. Experience in working with Agile & DevOps methodologies. Strong analytical and problem-solving skills with attention to detail. Excellent communication and stakeholder management abilities. Preferred Qualifications/Experience: Experience with performance testing tools (JMeter, LoadRunner, etc.). Knowledge of Kubernetes, Docker, or containerized environments. Certification in ISTQB, ITIL, or AWS/Azure Cloud services. Why Apply? 25 days annual leave bank holidays Up to 5% employer matched pension contribution L&D support, qualifications & L&D days Work on meaningful government projects Numerous health & insurance benefits Fantastic culture with regular social events Equal Opportunities: CACI is proud to be an equal opportunities employer. Embracing the diversity of our people, we are on a journey to build a truly inclusive work environment where no one is treated less favourably due to ethnic origin, age, gender, veteran status, religion or belief, sexual orientation, marital status, and disability or health condition, actively working to prevent discrimination. As a Disability Confident employer, we will; Provide reasonable adjustments in the recruitment process where requested (contact a member of the recruitment team on 020 7602 6000 to discuss individual requirements further). Offer people with health conditions and disabilities, meeting the minimum criteria for a role, an interview.