Principal C# Engineer / Snr Dev Lead in London

The consultant will operate as a senior development lead and principal-level C# / .

NET engineer within Risk, Product Control and ESG IT.

The role combines hands‑on engineering with solution design, stream leadership, technical oversight and delivery accountability across a CTB portfolio.

The role will support new product onboarding, feature delivery, methodology changes, platform enhancements, service modernisation and selected greenfield components.

The consultant is expected to remain substantially hands‑on, contributing approximately 25%-50% as an individual contributor, with the balance focused on coordination, design governance, mentoring, dependency management and delivery execution.

The technology stack is primarily C# / .

NET, supported by Mongo DB, SQL Server data warehouse components, enterprise messaging and Open Shift‑based container platforms.

The role will use the bank's internal developer platform capabilities to deliver secure, resilient, observable and portable services aligned to modern engineering and platform standards.

Duties and Responsibilities

• Lead technical analysis, solution design and hands‑on development of applications, services, APIs, event‑driven components, batch processes and platform‑aligned capabilities.
• Act as a C# / .

NET SME, setting engineering direction and ensuring solutions are clean, maintainable, testable and aligned to modern .

NET practices, SOLID principles and appropriate design patterns.

• Produce and review solution designs covering service boundaries, contracts, data models, integration patterns, idempotency, resilience, security, observability and operational supportability.
• Contribute directly to code delivery while reviewing implementation approaches, pull requests and engineering standards across the team.
• Lead delivery streams across internal and external resources, including work breakdown, estimation, sprint planning, technical triage, dependency management, risk management and stakeholder reporting.
• Apply and extend internal developer platform and platform engineering patterns, including shared .

NET libraries, reusable templates, golden paths, automated delivery, configuration and operational dashboards.

• Support migration from Windows‑hosted services to Open Shift, including containerisation, Helm‑based deployment, Kubernetes orchestration, scaling, storage integration, service mesh alignment and production readiness.
• Design and optimise integrations across Mongo DB, SQL Server / data warehouse components, REST APIs, enterprise data sources and messaging platforms such as Active MQ, Kafka or Redpanda.
• Design event‑driven solutions using appropriate messaging patterns including publish/subscribe, competing consumers, retries, dead‑letter handling, schema/version management and effectively‑once processing where required.
• Use AI‑enabled engineering tooling responsibly to improve delivery productivity, including integrated agentic coding assistants, prompt engineering, code review support and, where appropriate, agentic workflow patterns and MCP‑based integrations.
• Mentor developers and improve team capability across C# / . NET, Open Shift, Mongo DB, SQL, messaging, platform engineering and modern engineering practices.
• Ensure appropriate unit, integration, contract, regression, performance and system testing is applied, and support UAT, release preparation, cutover and early‑life support.
• Liaise with business users, methodology teams, delivery managers, support teams, platform teams and other ISD teams to ensure delivery remains aligned to business priorities, platform standards and control expectations.
• Adhere to development standards, SDLC processes, change control, information security and operational resilience expectations.

Qualifications, Skills and Experience

Essential Experience

• Extensive experience as a senior developer, technical lead, principal engineer, stream lead or development lead in a complex enterprise technology environment.
• Strong hands‑on C# / . NET development experience, with the credibility to lead senior engineers while still contributing directly to delivery.
• Experience producing solution designs, guiding implementation and coordinating work across multiple developers, workstreams or delivery partners.
• Experience delivering CTB change across production‑facing systems where resilience, supportability, auditability, security and controlled change are important.
• Experience applying engineering best practice including loose coupling, contract‑first design, idempotency, automated testing, secure coding, observability and operational readiness.
• Experience leading people to deliver, including mentoring, work allocation, delivery tracking, quality review and constructive challenge, while remaining substantially hands‑on.
• Experience working with business and IT stakeholders in a pressured delivery environment, ideally within financial services or another regulated industry.
• Technical Knowledge / Skills
• Expert knowledge of C# and strong knowledge of . NET Framework, . NET Core and modern . NET.
• Strong understanding of solution design, service boundaries, design patterns, SOLID principles, microservice architecture and scalable service design.
• Strong experience developing REST APIs and integration patterns, including contract‑first API design, versioning, validation, error models and backward compatibility.
• Strong document database knowledge, preferably Mongo DB, including schema design, indexing, aggregation, performance tuning, consistency trade‑offs and operational considerations.
• Strong relational database and SQL skills, including design, optimisation and data warehouse interaction.
• Strong knowledge of enterprise messaging and event‑driven architecture, ideally Active MQ, Kafka, Redpanda or equivalent, including message contracts, ordering, retries, DLQs and consumer resilience.
• Strong knowledge of container platforms and cloud‑native architecture, preferably Open Shift/Kubernetes, including Helm deployment, orchestration, scaling, service discovery, configuration and runtime operations.
• Good knowledge of Kubernetes ecosystem capabilities including KEDA or equivalent event‑driven scaling, Istio or equivalent service mesh, ingress/routing, secrets/configuration management and persistent volume/claim patterns using storage platforms such as Portworx.
• Good knowledge of automated testing and delivery practices, including unit, integration and contract testing, CI/CD pipelines, source control, quality gates and container image management.
• Practical experience with tooling such as JIRA, Bamboo, Git / Bitbucket, Nu Get and container image registries.
• Knowledge of platform engineering practices, internal developer platforms, golden paths, reusable templates, paved‑road adoption and self‑service delivery capabilities.
• Knowledge and practical experience of AI‑enabled development tooling, integrated agentic coding assistants and prompt engineering; experience designing agentic workflows or MCP‑enabled integrations is desirable.
• Risk IT, Product Control IT, ESG IT, regulatory technology or financial‑services domain experience is desirable.
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