By Greig Cowan (Head of AI & Data Science Innovation)
NatWest has partnered with UK AI start-up Cosine as part of the UK Government’s £500M Sovereign AI programme. The objective is to develop advanced AI systems that are built, trained, and operated entirely within UK-controlled infrastructure, with a strong focus on regulated industries.
At the centre of this effort is Isambard‑AI, one of Europe’s most powerful AI supercomputers. It provides the domestic compute needed to train large-scale models without relying on external providers.
Cosine is developing a sovereign large language model (LLM) designed for secure, high-sensitivity environments. The model is intended to run in private or fully air‑gapped settings where data must remain tightly controlled.
The technical approach combines modern model architecture with large-scale UK compute. In particular, Cosine is expected to use a Mixture-of-Experts (MoE) design, where only relevant parts of the model are activated for each request. This improves efficiency, enables larger effective model capacity, and performs well on specialised tasks such as coding and regulatory workflows.
This is supported by significant GPU allocation on Isambard‑AI, giving Cosine the scale needed to train frontier-level systems entirely within the UK.
NatWest is not just a consumer of the technology. Through a Memorandum of Understanding, it is part of a broader coalition helping shape the system from the outset.
Its contribution centres on three areas: providing real-world requirements from a regulated banking environment, offering feedback on model and product design, and participating in ongoing review cycles. This co-design approach ensures the technology is grounded in practical enterprise needs early in its development.
For financial services, AI adoption is constrained by strict requirements around privacy, compliance, and security. Many high-value use cases rely on sensitive data that cannot leave controlled environments.
Sovereign AI addresses this by enabling deployment in private infrastructure with full control over data, execution, and access. It also aligns more naturally with UK regulatory expectations, reducing the risks associated with cross-border data movement or external dependency.
This collaboration reflects a broader push to build a UK-based AI ecosystem that combines government-backed compute, domestic AI developers, and industry participation. The focus is shifting from simply accessing powerful models from frontier labs to ensuring those AI models can be operated safely and effectively in critical sectors. If successful, it provides a path to adopt advanced AI capabilities while maintaining the control, security, and governance that organisations require.
<hr><p>NatWest and Cosine: Building Sovereign AI in the UK was originally published in NatWest Group AI & Engineering on Medium, where people are continuing the conversation by highlighting and responding to this story.</p>