Location: Luton (4 days per week onsite) Duration: 12 month contract Rate: £78ph UMB (Inside IR35) Role details: Our client, a leading organisation in the Defence & Security sector, is currently seeking a Principal Software Engineer specialising in C# and .NET for a contract role based in Luton. This position offers the unique opportunity to work on cutting-edge defence technology within a mature development environment. Key Responsibilities: Develop robust applications using C# .NET within a Windows environment. Take ownership of complex tasks across the full software lifecycle-from requirements to integration, testing, and delivery. Apply object-oriented design principles and verification/validation techniques. Collaborate with a skilled team while maintaining independence in your work. Job Requirements: Proven experience in C# .NET development, including web-based applications. Strong understanding of object-oriented design and software development methodologies. Experience across the full software lifecycle, including automated testing frameworks and practices. Experience with Continuous Integration / Continuous Delivery (CI/CD) practices. Ability to work independently and deliver high-quality solutions with minimal supervision. Experience with Agile methodologies (Scrum, Kanban) and microservices architecture. Desirable: Defence or Electronic Warfare domain experience. Familiarity with frameworks/tools such as WPF, WinForms, Visual Studio. Knowledge of DOORS, Cameo, and Azure DevOps. Some experience with C++. If you are an experienced C# .NET developer looking for a challenging and rewarding contract position in the Defence & Security sector, we would love to hear from you. Apply now to join our client's innovative team in Luton.