Location: Bristol, On-site, 5 days per week (due to project classification) Salary: Up to £64,000 bonus & excellent benefits Clearance: British Citizen or Dual UK National with British citizenship Copello are working with a leading defence technology partner seeking a Principal Software Engineer to join their Human Machine Interface (HMI) and Cyber team, developing cutting-edge laser defence systems for the Royal Navy. The Role You’ll take a leading role in the technical delivery of complex software solutions, mentoring junior engineers and ensuring high standards across design, implementation, and integration. What You’ll Bring * Strong proficiency in C++ * Proven experience delivering complex software systems end-to-end * Solid understanding of the software development lifecycle * Excellent problem-solving, communication, and mentoring skills Desirable experience: OS lockdown, software security, HMI development, or automated testing. Benefits Include * Up to £2,500 annual bonus (performance-based) * Pension up to 14% combined contribution * Flexi leave (up to 15 extra days) * Enhanced parental leave * Paid overtime and flexible working arrangements * Excellent on-site facilities including subsidised meals and free parking If you’re a passionate, analytical engineer who thrives on solving complex challenges - we’d love to hear from you