Evolutionary Optimisation - Member of Technical Staff
Possible
Sponsorship likelihood
This employer issued few or no visas recently
£101,000 – £192,000 / year
Salary
Above P75 for SOC 2134
£54,700
Going rate
Offer clears by 1.8×
This role likely qualifies for a Skilled Worker visa
SOC 2134 (88% match) is an eligible occupation, with a going rate of £54,700, and CALLOSUM LTD is a licensed sponsor. That is our reading of the rules. Whether they issue a Certificate of Sponsorship is still their call.
This could also be SOC 2133 (IT business analysts, architects and systems designers, Focus on systems design and integration across hardware/software stack) or SOC 2129 (Engineering professionals not elsewhere classified, Engineering n.e.c. if seen as broader engineering R&D role). We read the code off the advert, so it is our best guess, not the employer's.
New graduate or PhD holder? Pick one of the lower rates.
What each route needs for this job
| Occupation code | New entrant 70% of going rate | STEM PhD 80% of going rate | Relevant PhD 90% of going rate | Standard rate 100% of going rate |
|---|---|---|---|---|
2134 Programmers and software development professionals Most likely code | £38,300 Clears | £43,700 Clears | £49,200 Clears | £54,700 Clears |
2133 IT business analysts, architects and systems designers Also possible | £38,400 Clears | £43,900 Clears | £49,400 Clears | £54,900 Clears |
2129 Engineering professionals not elsewhere classified Also possible | £33,400 Clears | £36,900 Clears | £41,500 Clears | £46,100 Clears |
We use the lowest threshold across the plausible codes. Likelihood is Possible at most when the pay clears only a lower rate, or only under a less likely code. A mark is for the top of the advertised pay. How the Home Office picks the code
About the role
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 believes that the next generation of AI systems will be co-optimised across models, software, and hardware. As we operate across increasingly heterogeneous workloads and accelerators, the number of possible system configurations grows combinatorially. Manually exploring that space does not scale – we need systems that can search it themselves.
This role owns Callosum’s program evolution and optimisation loop: an LLM-guided search system that iteratively generates, evaluates, and improves programs against verifiable objectives. We already use this approach across kernels, inference runtimes, scheduling and scaling policies, KV caching strategies, and more. You will develop the loop both as a reusable internal optimisation system and as a research object in its own right, improving how it searches, measuring what makes it effective, and pushing its capabilities on increasingly difficult optimisation and reasoning problems.
What You'll Build
Develop the core program evolution loop, improving how candidates are generated, evaluated, selected, and evolved over long optimisation runs
Design search strategies that balance exploration, exploitation, diversity, and sample efficiency across vast and irregular optimisation spaces
Build continuous benchmarks that measure the optimiser across internal workloads and standalone problems, making improvements and regressions empirically visible
Turn the system into reliable internal infrastructure that can optimise new verifiable domains as a reusable internal tool that other team members can scale to new problems
What Sets You Apart
Strong foundations in optimisation and search, including familiarity with evolutionary, stochastic, combinatorial, or other non-gradient-based methods
Ability to reason about search itself i.e. exploration versus exploitation, diversity, pruning, objective design, and when different optimisation strategies are appropriate
Strong engineering instincts, with experience turning experimental systems into reusable, measurable, and reliable software
A demonstrable tendency to draw from techniques across optimisation, algorithms, and machine learning rather than treating LLMs as the solution to every problem
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.
This description is the source posting as it read when we added it. We are not affiliated with CALLOSUM LTD, so check their own site for the current details.
Where this offer sits in the market
Programmers and software development professionals (SOC 2134) · UK · ONS ASHE 2025 · basic pay · ~399k in sample- Offer £101,000–192,000
- Middle half £42,536–76,752
- Median £56,784
- Going rate £54,700
- Threshold £41,700
- New entrant £38,300–49,200
Even the bottom of this range, £101,000, beats the market's 75th percentile. CALLOSUM LTD pays in the top quarter for this occupation.
Similar sponsored roles
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Does this job guarantee visa sponsorship?
Not necessarily. CALLOSUM LTD holds a sponsor licence, but sponsorship for a specific hire is always the employer's decision. Be upfront in your application that you'll require it.
What salary is needed for this role to be eligible?
The offer must clear both the general threshold and the SOC 2134 going rate of £54,700. New-entrant and shortage discounts can lower it.