Salary: £90,000 - 90,000 per year Requirements: We are looking for a Senior Software Engineer with strong hands-on experience in complex technical environments. We require strong Python development skills. We would value experience with C or C++ codebases, bindings, integrations, or interoperability. We need experience maintaining, refactoring, or modernising existing or legacy software systems. We are looking for strong debugging, problem-solving, and root cause analysis skills. We need the ability to investigate complex incidents and deliver durable, well-engineered fixes. We require understanding of software architecture, maintainability, reliability, and performance considerations. We value experience with peer review, engineering standards, quality gates, and technical documentation. We need someone who can mentor other engineers and provide technical leadership in a hands-on capacity. We require comfort working in structured delivery environments where evidence, quality, and engineering discipline are important. We would consider experience with MATLAB or Simulink integration as desirable. We would consider experience in scientific, engineering, defence, aerospace, simulation, modelling, or complex systems software as desirable. We would consider exposure to performance optimisation, systems integration, or high-assurance environments as desirable. We would consider experience supporting architecture evolution or major codebase upgrade programmes as desirable. We require MOD DV Clearance. Responsibilities: We lead hands-on software maintenance, enhancement, and upgrade work across complex codebases. We investigate defects, incidents, and technical issues, carrying out root cause analysis and implementing robust fixes. We refactor and improve existing software to increase maintainability, reliability, and performance. We support architecture adaptation and evolution as system requirements change. We work across Python-based systems, including integration with C/C++ components or bindings where required. We contribute to codebase modernisation, engineering standards, tooling improvements, and quality processes. We support performance analysis and deliver improvements where needed. We mentor engineers, provide technical guidance, and help raise engineering quality across the team. We contribute to peer review, quality gates, and engineering governance. We produce technical evidence, documentation, and supporting material for project deliverables. We support planning activity, estimation, acceptance criteria, and delivery inputs. Technologies: Support Matlab Python More: We are a leading technology consultancy delivering complex software engineering, maintenance, and modernisation projects. This is a permanent Senior Software Engineer role based in Portsmouth with home working, requiring on-site presence three days a week. The salary is £80,000 to £90,000 plus benefits. This is a hands-on senior engineering position focused on maintaining, improving, and evolving complex software systems, and it would suit someone who enjoys technically challenging codebases where reliability, maintainability, and engineering quality are critical. last updated 21 week of 2026