Principal Engineer (AWS & Java) in London

We are seeking a Principal Engineer to act as the most senior hands-on technical expert for our leading Risk Screening platform. This role partners closely with architecture, service, product, and engineering teams to ensure that agreed designs are implemented to the highest technical and operational standards.

A core focus of the role is ownership of the system’s non-functional characteristics, including end-to-end latency, cloud scalability, resilience, and the effective handling of large and growing data sets. The Principal Engineer ensures these qualities are deliberately designed for, correctly implemented, and continuously validated in production.

Rather than owning architecture in isolation, the Principal Engineer is the expert implementor and problem solver: translating architectural intent into robust, performant, and secure production systems. This is the most senior individual contributor role with broad influence, focused on technical excellence, delivery confidence, and long-term sustainability.

• Act as the senior-most technical authority for implementation within the Risk Screening platform.
• Partner with enterprise and solution architects to validate designs, challenge assumptions, and guide effective development approaches.
• Lead the implementation of the most complex and business-critical changes, setting the standard for quality, performance, and maintainability.
• Provide hands-on expertise in Java-based systems, including concurrency, performance tuning, memory management, and API design.

• Define, implement, and validate non-functional requirements such as latency, throughput, scalability, and reliability.
• Drive solutions for cloud scaling and capacity management to ensure predictable performance under variable and peak loads.
• Optimize large databases and data stores for performance, access patterns, and operational scaling.

• Solve complex technical problems spanning multiple components or teams.
• Serve as a point of escalation for deep technical issues that require system-level understanding.
• Support engineering teams in making sound technical decisions, clarifying trade-offs and long-term consequences.

• Guide teams on best-practice use of AWS services with a focus on elastic scaling and performance under load.
• Ensure implementations support horizontal and vertical scaling, efficient resource utilisation, and predictable behaviour as demand grows.
• Review autoscaling, workload management, and cost-efficiency to align with agreed architectures.

• Identify operational risks, scaling limits, and reliability concerns proactively.
• Improve resilience, monitoring, alerting, and incident prevention informed by production behaviour.
• Partner with Site Reliability Engineers and operations teams to reduce customer impact.

• Champion engineering standards across coding, testing, deployment, and operational readiness.
• Conduct deep technical reviews of critical changes focusing on performance, security, and reliability.
• Help teams reduce technical debt through incremental improvements aligned to product priorities.

• Act as a technical mentor and coach to senior engineers and technical leads.
• Support engineers in developing stronger implementation skills and deeper system-level thinking.
• Influence engineering culture through example, constructive challenge, and practical excellence.

• Extensive experience as a Principal Engineer or equivalent senior technical role on large-scale production systems.
• Hands-on expertise in Java (Java 11+ preferred), including JVM behaviour, concurrency, and performance optimisation.
• Practical experience building and running systems on AWS with real-world operational trade-offs.
• Proven ability to implement and operate distributed systems at scale, emphasizing performance and scalability.
• Experience with large databases or data platforms, including performance tuning and operational management.
• Understanding of production operations, incident management, observability, and reliability engineering.
• Ability to influence and guide teams through technical credibility rather than formal authority.

We are proud to be an equal opportunities employer. We do not discriminate on the basis of race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy, disability, or any other basis protected by applicable law. We accommodate religious practices, mental health, and physical disability needs as required by law.