AI Security Engineer in City of London

Why work for us? A career at Janus Henderson is more than a job, it’s about investing in a brighter future together. Our Mission at Janus Henderson is to help clients define and achieve superior financial outcomes through differentiated insights, disciplined investments, and world-class service. We will do this by protecting and growing our core business, amplifying our strengths and diversifying where we have the right. 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: This is a hands-on security engineering role for people who are deep in cybersecurity and serious about AI. You will secure the AI systems we are building — AI-enabled applications, models, agents, and the platforms beneath them, across their full lifecycle — acting as a trusted advisor who helps define and evolve the firm’s AI security standards, patterns, and guardrails. The objective is not to create additional process, but to ensure our existing security capabilities evolve alongside AI adoption and remain effective at enterprise scale.

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 builds and runs it. This role sits in Information Security and reports to the Head of Security Engineering, while your day-to-day work is directed by AI Technology and prioritised against their roadmap. That split is deliberate: security policy, security architecture approval, and security risk acceptance stay with Infosec, and you are the person who exercises them for AI — close enough to the engineering to be useful, independent enough to say no.

You will secure Nexus, our agentic workspace where employees and citizen developers build and run AI applications, agents, and shared skills; Accio, our centralised MCP server, which consumes other MCP servers and presents enterprise datasets through one governed interface; the AI model gateway and its routes to external model providers; and our Copilot services. Accio and Nexus matter most: both propagate permissions and data on a user’s or an agent’s behalf, so their trust boundaries have to hold when a request crosses several hops. Throughout, you will balance effective risk management against the velocity needed to deliver AI solutions that drive business value and growth.

A secondary focus of the role is partnering with the wider Security function to identify opportunities to leverage AI and automation to improve efficiency, effectiveness, and risk reduction across security operations, engineering, assurance, and governance — so that the controls you design are enforced and evidenced automatically rather than through review meetings.

What success looks like: Security is designed into AI systems rather than appended. Engineers reach for an approved pattern instead of asking for a bespoke review. The controls you define are implemented as code and secure defaults by AI Engineering and AI Platforms, and you can show they are operating. AI-specific attacks are anticipated and tested for, and you can demonstrate what the firm is and is not exposed to. New models, tools, and Copilot features reach a security decision quickly through a repeatable risk-based path, and when an AI incident happens the lesson lands in a platform default rather than a report. Risk reduction and control effectiveness are evidenced through agreed KPIs, KRIs, and reporting rather than asserted.

Your responsibilities:

• Secure the AI estate by design.
• Act as security design authority for AI systems, leading threat modelling, architecture review, and risk assessment for agentic applications, the model gateway, Accio, Nexus, and any novel or high-risk AI initiative, applying STRIDE, PASTA, MITRE ATT&CK, and MITRE ATLAS as appropriate.
• Define and evolve AI security standards, guardrails, governance controls, and secure-by-design patterns aligned with enterprise requirements and the firm’s risk appetite.
• Design identity, entitlement, and secrets patterns for non-human identities.
• Set the trust boundaries and data-egress controls for the AI estate.
• Run adversarial testing and AI red teaming against models, prompts, agents, and tool chains.
• Build detections, security analytics, and telemetry for AI-specific abuse.
• Support security incident response for AI systems.
• Own security testing in the AI delivery lifecycle.
• Co-own the risk-based security gate for onboarding new AI products.
• Support Risk and Internal Audit with security evidence.
• Identify and deliver opportunities to apply AI and automation across security operations.
• Define and report the KPIs, KRIs, dashboards, and reporting that demonstrate risk reduction.
• Mentor security engineers on AI security.

What to expect when you join our firm:

• Hybrid working and reasonable accommodations.
• Generous Holiday policies.
• Excellent Health and Wellbeing benefits.
• Paid volunteer time.
• Support to grow through professional development courses.
• 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.

Must have skills:

• Strong cybersecurity experience across security engineering, application security, product security, cloud security, or security architecture.
• Hands-on experience assessing and securing GenAI, LLM, machine learning, agentic AI, and AI-enabled solutions.
• Proven ability to lead threat modelling, architecture reviews, and risk assessments.
• Strong understanding of AI-specific threats and methodologies.
• Experience defining and evolving AI security standards.
• Experience securing AI agents, MCP integrations, permissions, and workflows.
• Cloud security depth, ideally Azure.
• Practical experience with AI and LLM systems.
• Metrics-driven mindset.
• Strong stakeholder engagement and influencing skills.

Nice to have skills:

• Familiarity with AI security and governance frameworks.
• AI red teaming and adversarial testing experience.
• Experience securing enterprise AI platforms.
• Knowledge of AI security posture management.
• Experience applying AI and automation to vulnerability management.
• Understanding of privacy, data governance, regulatory, and responsible AI considerations.

Supervisory responsibilities: No. This is an individual-contributor role reporting into Information Security.

Potential for growth: Mentoring, Leadership development programs, Regular training, Career development services, Continuing education courses.

At Janus Henderson Investors we’re committed to an inclusive and supportive environment. We believe diversity improves results and we welcome applications from candidates from all backgrounds.

Annual Bonus Opportunity: Position may be eligible to receive an annual discretionary bonus award from the profit pool.

Benefits: Janus Henderson is committed to offering a comprehensive total rewards package to eligible employees.

Janus Henderson Investors is an equal opportunity employer. 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.