At a Glance
- Tasks: Lead security architecture and assurance across diverse technical environments.
- Company: Join Callosum, a pioneering Intelligent Systems Company in London.
- Benefits: Competitive salary, equity, private healthcare, and relocation support.
- Other info: Inclusive workplace with opportunities for personal and professional growth.
- Why this job: Shape the future of AI security in a dynamic, innovative environment.
- Qualifications: Proven experience in security assurance and team leadership.
The predicted salary is between 80100 - 97900 £ per year.
About Us
We’re living through a Cambrian explosion of intelligence: new models and new chips, each specialised for different tasks, are arriving all at once. The result is a new era for AI, one of radical heterogeneity. Callosum is the Intelligent Systems Company. We believe the next generation of AI won't be defined by any single model or chip, but by intelligent systems in which hardware and intelligence co-evolve. We are building the infrastructure that unifies heterogeneous compute across the full stack. This opens a new axis of scaling intelligence: a dynamic system that tailors itself to what each workload actually needs, whether that's speed, cost, precision, or whatever unit comes next.
The last era scaled on a different bet: one bigger model, more of the same chip, more data. That bet is running into structural limits. Frontier models offer extraordinary capability at unsustainable cost, one that today's monolithic infrastructure was never designed to serve. Our founding principle is that intelligence comes from many specialised systems working together, not from any single component. We build the software orchestration layer that co-evolves models, workflows and silicon into one system, delivering inference tailored to every workload, and demonstrating orders-of-magnitude leaps in capability and cost.
Because our software spans the full stack, our engineering team works directly with heterogeneous accelerators and frontier silicon, including Cerebras, d-Matrix, Intel, NVIDIA, AMD, Normal Computing, Tenstorrent, GreatSky, and Mixx. We are not stopping at today's chips: each new generation of silicon unlocks algorithms that couldn't run before, and we intend to be first to them, every time. If we get it right, it will belong to everyone building on it - not to any single vendor. In our latest funding round, we raised $100M, led by Atomico with participation from Plural, DCVC and the UK Sovereign AI Fund’s first investment. With this, we are building the infrastructure for the next era of intelligence.
We are engineers and scientists based in London, working across the full depth of the stack. We are curious, intellectually honest, and building what doesn't exist yet. If you thrive on uncharted territory and are energised by the scale of the challenge, we'd love to hear from you.
About the Role
Callosum operates across a broad technical surface: APIs used by customers directly, orchestration software deployed across heterogeneous clusters, agentic systems with access to tools and data, and physical compute infrastructure that we operate ourselves. These products run in very different environments and for customers with very different security requirements, from shared cloud infrastructure through to sovereign, on-premise, and isolated deployments. This role owns how security is designed and assured across that landscape. You will set the security architecture, translate customer and deployment requirements into concrete technical expectations for engineering teams, and ensure that the guarantees we make can be demonstrated in practice. You will lead security engagements across customers, infrastructure partners, and external technical reviewers, while building and managing the team responsible for security across Callosum.
What You'll Do
- Define security architecture and requirements across our API, orchestration stack, agentic systems, and physical infrastructure
- Translate complex security requirements into specific engineering work, measurable guarantees, and verifiable evidence
- Lead security assurance for sensitive deployments from initial requirements through technical review and approval
- Build and lead the security team across architecture, threat modelling, adversarial evaluation, incident response, and operations
What Sets You Apart
- Experience personally owning a demanding security assurance or sensitive deployment process end-to-end
- Strong technical foundations in infrastructure or security engineering, with the depth to challenge architectural decisions
- Experience securing sovereign, on-premise, air-gapped, multi-tenant, or other high-assurance environments
- Experience building and leading security teams, with strong judgement around risk, prioritisation, and engineering trade-offs
What We Offer
- Competitive Salary, determined by skills and experience
- Equity & Ownership
- Private healthcare
- We offer Visa sponsorship and relocation benefits to hire the best in the world
- We work in person at our London office. You'll have the tools, space and setup to do your best work, and if you have specific needs, just tell us
- We're committed to building an inclusive workplace where everyone feels welcome, and believe in equal opportunities for all.
Security Lead - Member of Technical Staff in London employer: Callosum
At Callosum, we pride ourselves on being an exceptional employer that fosters a culture of innovation and collaboration. Our team thrives in a dynamic environment where tackling complex challenges is not just encouraged but celebrated, offering ample opportunities for professional growth and development. Located at the forefront of AI technology, we provide our employees with access to cutting-edge resources and a supportive community that values diverse perspectives and ideas.
StudySmarter Expert Advice🤫
We think this is how you could land Security Lead - Member of Technical Staff in London
✨Get Involved in the Cybersecurity Community
Diving into the cybersecurity community is key for landing that full-time gig. Join forums like Reddit's r/cybersecurity or attend local meetups to connect with industry veterans and other job seekers. Networking is everything in this field—don’t just be a passive lurker!
✨Show Off Your Skills with Capture the Flag Competitions
Participate in Capture the Flag (CTF) competitions; these are not just a fun way to boost your skills but also a chance to showcase your talent to potential employers. Many companies, including Callosum, love seeing candidates who actively engage in these challenges.
✨Tailor Your Online Presence
Make sure your LinkedIn and any professional profiles reflect your cybersecurity expertise. Share your projects, whether they’re personal or from a previous role, to catch the eye of hiring managers. This is how they’ll find your passion and commitment to the field!
✨Apply Directly Through Callosum
Don’t forget to head straight to our website and check out any openings for cybersecurity roles at Callosum. Applying directly can sometimes give you an edge, especially if you can mention that you've been following our work or engaging in the community.
We think you need these skills to ace Security Lead - Member of Technical Staff in London
Some tips for your application 🫡
Show off your technical skills:In cybersecurity, it's crucial to highlight your technical prowess. Make sure your CV showcases specific skills like network security, penetration testing, or threat analysis. If you have relevant certifications (like CEH or CISSP), pop those on the front page to grab attention!
Tailor your portfolio for the role:Even for a full-time role, a portfolio can set you apart. If you've worked on any cybersecurity projects—be it CTF challenges, security assessments, or research papers—include these in your application. This demonstrates not just your skills, but also your hands-on experience!
Use real-world examples:When writing your cover letter, don’t just stick to your qualifications. Share real-world examples of how you’ve tackled security issues or vulnerabilities. This gives the hiring team at Callosum insight into your practical problem-solving abilities and makes your application memorable.
Demonstrate your passion for cybersecurity:Cybersecurity is an ever-evolving field, so show us that you’re always learning! Mention any recent courses, webinars, or industry events you’ve attended. This not only exhibits your enthusiasm but also signals to Callosum that you’re committed to staying ahead in the game.
How to prepare for a job interview at Callosum
✨Sharpen Your Technical Skills
For a role in cybersecurity, it’s essential to be up-to-date with the latest tools and techniques. Brush up on your knowledge of firewalls, intrusion detection systems, and vulnerability assessment tools. Be ready to discuss specific scenarios where you’ve applied these skills, as hands-on experience can really set us apart in interviews.
✨Prepare for Scenario-Based Questions
Expect the interviewers at Callosum to throw in some hypothetical situations to see how you’d handle them. Think about common security breaches or incidents and be prepared to explain how you would respond. This not only shows your problem-solving skills but also your understanding of real-world cybersecurity challenges.
✨Highlight Your Certifications
Certifications like CompTIA Security+, CISSP, or CEH can give you a significant edge in a full-time role in cybersecurity. Make sure to mention these during your interview and be prepared to discuss what you learned through those certifications and how they relate to the position at Callosum.
✨Show Your Passion for Cybersecurity
Since you’re going for a full-time gig, showing genuine enthusiasm for the field can make all the difference. Share any personal projects, blogs, or communities you’re part of that relate to cybersecurity. This not only showcases your passion but also your commitment to staying engaged in this ever-evolving field.
