Principal Engineer - Active SC, 4GL Up to £640 per day (Inside IR35) London / Remote 12 Months My client is an instantly recognisable consultancy who require a Principal Engineer with Active NPPV3 and Active Security Clearance (SC), to help lead a business critical project for an end client. Key Requirements: Proven experience as a Principal Engineer Active NPPV3 and Active Security Clearance (SC) Proven experience leading multiple engineering teams on complex, large-scale projects Strong capability in stakeholder engagement across technical and non-technical groups Demonstrated leadership and mentoring skills, supporting the growth and development of engineers Experience with backlog refinement and preparing high-quality user stories In-depth knowledge of a fourth-generation programming language (4GL) Strong skills in object-oriented analysis and design (OOAD) Proven experience with C#, Java (Spring Boot, JPA/Hibernate), REST APIs, observability, monitoring, queue technologies, security, and relational databases (especially Postgres). Strong understanding of SOLID principles, microservice development focused on high availability and data integrity, and solid use of JUnit, TDD, and integration/end-to-end testing. Nice to have: Proven experience in JavaScript or Vue.js for front-end development. Exposure to AWS and DevOps tooling such as Docker, Terraform, Kubernetes, Helm, and Git. Exposure to PHP or Drupal. Exposure to WordPress optimisation, including caching, CDN integration, and database tuning. If you're interested in this role, click 'apply now' to forward an up-to-date copy of your CV, or call us now. If this job isn't quite right for you, but you are looking for a new position, please contact us for a confidential discussion about your career. Hays Specialist Recruitment Limited acts as an employment agency for permanent recruitment and employment business for the supply of temporary workers. By applying for this job you accept the T&C's, Privacy Policy and Disclaimers which can be found at hays.co.uk