Senior Python - AI Developer in London

Our Mission at Janus Henderson is to help clients define and achieve superior financial outcomes through differentiated insights, disciplined investments, and world-class service. Our Values are key to driving our success, and are at the heart of everything we do: Clients Come First - Always | Execution Supersedes Intention | Together We Win | Diversity Improves Results | Truth Builds Trust. If our mission, values, and purpose align with your own, we would love to hear from you!

Your opportunity: Janus Henderson is undertaking a firm-wide AI transformation to become the most technologically sophisticated asset manager in the industry. Our AI capability sits in a single centralised function under the Head of AI, and AI Technology is the part of it that builds, governs, and runs the software. AI Engineering is the core product and platform engineering team within it.

As a Senior Applied AI Engineer, reporting to the Principal AI Engineer, you will lead the delivery of major parts of that estate — designing and building agentic applications and platform services, taking them through evaluation and our AI governance checkpoints into production, then owning them once live. You will set implementation patterns alongside AI Architecture, review other engineers' work, and be the person the team turns to when a production system behaves in a way nobody predicted.

You will also own the end-to-end build of business applications for specific parts of the firm — not only the horizontal products every team shares, but targeted applications built on the AI stack for a named business area, carried from first requirement through to a supported production service. Much of this work is deliberate SaaS decommissioning: where a capability currently bought as a SaaS subscription can be built in-house instead, you own that build end-to-end and see the displaced product retired, so the firm consolidates onto governed, in-house capability rather than paying for overlapping tools.

Your toolkit spans Python and SQL, LLMs and agent frameworks, MCP, Azure AI Foundry through the AI Team's model gateway, Snowflake and Microsoft Fabric, and Azure with Terraform, Docker, and CI/CD. AI Engineering is being established for the first time here, so you will shape how the team works rather than inherit a settled routine.

Your responsibilities:

• Build and run our AI products and platform.
• Design, build, and productionise AI products and shared platform services, taking a workstream end to end and owning it through to live running.
• Build for reuse, turning capability proven in one product into shared components, libraries, skills, tools, MCP servers, and connectors.
• Build the orchestration layer that long-running and multi-step agents depend on, covering permissions, workload isolation, safe execution, and the applications built on it.
• Test the claims made for new models, frameworks, and patterns before recommending we adopt them.
• Make enterprise data AI-ready.
• Build governed, AI-ready views, indexes, semantic context, and connectors over Snowflake, enterprise platforms, APIs, and external providers.
• Extend Accio so new datasets and downstream MCP servers are reachable through one governed interface rather than one-off integrations.
• Build ingestion pipelines and data models where source data does not arrive usable, while canonical source ownership stays with the relevant Technology team.
• Own lineage, quality, and freshness for the data your products depend on, and implement least-privilege access for users, agents, tools, and service identities.
• Own the end-to-end build of targeted business applications on the AI stack — Distribution first, then areas such as trading, investment risk, client servicing, and operations — delivered for a named business owner rather than for every team at once.
• Drive SaaS decommissioning: where a bought subscription can be replaced by an in-house build, own the delivery of that replacement end-to-end, see the displaced product retired, and work with Procurement and Finance to consolidate the licence.
• Build evaluation and control, and work with the team.
• Build evaluation and regression suites for models, prompts, agents, and platform changes, meet the agreed thresholds before release, and instrument what you build for quality, safety, reliability, latency, drift, usage, and cost.
• Implement the controls defined by AI Governance Implementation and AI Security as code and secure defaults, and produce release evidence proportionate to the risk of the use case, generated by the platform rather than assembled after the event.
• Mentor AI Engineers through pairing, design discussion, and code review, and help establish the team's engineering standards, agentic SDLC, and definition of done.
• Work with AI Architecture to turn reference patterns into implementations teams use, partner with Forward Deployed Engineering so proven solutions become supported shared capability, and feed adoption data from the AI Enablement Partners into the backlog.

Must have skills:

• At least six years in software, data, or platform engineering, with a track record of shipping and operating production systems rather than prototypes.
• Production experience with LLM applications and agentic systems, covering prompt and context engineering, agent development, retrieval, tool use, evaluation, and deployment at scale.
• Strong Python and SQL, with the judgement to write code others can maintain and extend.
• Hands-on experience building agentic capability such as MCP servers, tools, skills, or connectors for other systems and agents to consume.
• Experience owning services in production — monitoring, incident investigation, upgrades, lifecycle management — and establishing evaluation and observability for AI systems.
• Good judgement in a regulated environment, translating security, privacy, risk, and audit requirements into working technical controls.

Nice to have skills:

• Asset management or financial services domain knowledge, particularly the investment process, distribution, or front-office workflows.
• Azure AI Foundry, Azure OpenAI, Anthropic Claude, model gateways, inference routing, or agent orchestration platforms.
• Snowflake, Microsoft Fabric / OneLake, or comparable governed enterprise data platforms.
• TypeScript or a second production language, and front-end experience for user-facing AI applications.
• Experience building internal developer platforms or golden-path patterns used by other engineering teams, or taking partner-built software into internal ownership.

What to expect when you join our firm:

• Hybrid working and reasonable accommodations.
• Generous Holiday policies.
• Excellent Health and Wellbeing benefits including corporate membership to Wellhub.
• Paid volunteer time to step away from your desk and into the community.
• Support to grow through professional development courses, tuition/qualification reimbursement and more.
• Maternal/paternal leave benefits and family services.
• All employee events including networking opportunities and social activities.
• Lunch allowance for use within our subsidized onsite canteen.

Supervisory responsibilities: No. The Senior Applied AI Engineer leads technical delivery, sets implementation standards, and mentors AI Engineers, but does not line-manage. The role may act as technical lead for a product or platform workstream.

We believe diversity improves results and we welcome applications from candidates from all backgrounds. We understand everyone has different commitments and while we can't accommodate every flexible working request we're happy to be asked about work flexibility and our hybrid working environment. If you need any reasonable accommodations during our recruitment process, please get in touch and let us know at recruiter@janushenderson.com.

Annual Bonus Opportunity: Position may be eligible to receive an annual discretionary bonus award from the profit pool. Individual bonuses are determined based on Company, department, team and individual performance.

Janus Henderson is committed to offering a comprehensive total rewards package to eligible employees that includes; competitive compensation, pension/retirement plans, and various health, wellbeing and lifestyle benefits. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability or veteran status. You will be expected to understand the regulatory obligations of the firm, and abide by the regulated entity requirements and JHI policies applicable for your role.