Senior Software Engineer

Senior Software Engineer

All candidates should make sure to read the following job description and information carefully before applying.
Permanent
Location: Portsmouth / Home (on site 3 days a week)
Salary: £80,000 - £90,000 (+ benefits)
Skills: Python / C++ / Legacy Modernisation / Complex Systems, MOD DV Clearance
We are looking to recruit a MOD DV Cleared Senior Software Engineer for a leading technology consultancy delivering complex software engineering, maintenance and modernisation projects.
This is a hands-on senior engineering role focused on maintaining, improving and evolving complex software systems. The role would suit someone with strong Python development experience, ideally combined with exposure to C/C++ integration , performance improvement, refactoring, legacy system modernisation or engineering-heavy environments.
You will work on technically challenging codebases where reliability, maintainability and engineering quality are critical. This will include:
Investigating complex defects and incidents
Performing root cause analysis
Implementing durable fixes
Refactoring and improving existing software
Supporting architecture changes as requirements evolve
Helping modernise codebases, tooling and engineering standards
The role requires someone who is comfortable working across established systems, improving existing code and supporting other engineers through mentoring, review and technical leadership.
Key Responsibilities
Lead hands-on software maintenance, enhancement and upgrade work across complex codebases
Investigate defects, incidents and technical issues, carrying out root cause analysis and implementing robust fixes
Refactor and improve existing software to increase maintainability, reliability and performance
Support architecture adaptation and evolution as system requirements change
Work across Python-based systems, including integration with C/C++ components or bindings where required
Contribute to codebase modernisation, engineering standards, tooling improvements and quality processes
Support performance analysis and deliver improvements where needed
Mentor engineers, provide technical guidance and help raise engineering quality across the team
Contribute to peer review, quality gates and engineering governance
Produce technical evidence, documentation and supporting material for project deliverables
Support planning activity, estimation, acceptance criteria and delivery inputs
Skills & Experience
Strong hands-on software engineering experience in complex technical environments
Strong Python development skills
Experience working with C or C++ codebases, bindings, integrations or interoperability would be highly beneficial
Experience maintaining, refactoring or modernising existing/legacy software systems
Strong debugging, problem-solving xwzovoh and root cause analysis skills
Ability to investigate complex incidents and deliver durable, well-engineered fixes
Understanding of software architecture, maintainability, reliability and performance considerations
Experience with peer review, engineering standards, quality gates and technical documentation
Ability to mentor other engineers and provide technical leadership in a hands-on capacity
Comfortable working in structured delivery environments where evidence, quality and engineering discipline are important
Desirable Experience
Experience with MATLAB or Simulink integration
Experience working on scientific, engineering, defence, aerospace, simulation, modelling or complex systems software
Exposure to performance optimisation, systems integration or software used in high-assurance environments
Experience supporting architecture evolution or major codebase upgrade programmes