Cosine, a British sovereign AI frontier lab founded in London in 2023 and selected by the UK government as part of its sovereign AI initiative, has unveiled a coalition of major UK institutions to co-design Lumen Sovereign, the country’s first sovereign frontier AI model.
The coalition includes some of Britain’s most prominent organisations, with Babcock International Group, BT, Lloyds Banking Group, LSEG, NatWest Group, PwC, Thales UK, Leonardo UK, BAE Systems and Telefónica Tech UK&I among those signing memoranda of understanding to participate in the model’s design phase.
The full list of coalition partners also includes Era4, Haleon and The Alan Turing Institute. Lumen Sovereign will be trained entirely on Isambard-AI, one of Europe’s most powerful supercomputers, using compute allocated through the UK government’s £500m Sovereign AI programme, with deployment readiness targeted by the end of 2026.
MOU signatories will collaborate directly with Cosine to establish the use cases, security requirements and governance standards the model must satisfy. Critically, Lumen Sovereign is built to run entirely within a customer’s own infrastructure, with no external data transfer, a design principle increasingly seen as essential among institutions operating in highly regulated or sensitive environments. To support the breadth of coalition members’ needs, Cosine has assembled one of the largest collections of domain-specific training datasets outside the hyperscalers, covering more than 30 regulated industry workflows.
Priority applications for the model span workflows where data sensitivity has historically made AI adoption difficult. These include cybersecurity and adversarial testing, KYC and AML alert investigation, clinical trial coordination, legal document review and healthcare administration.
Unlike models fine-tuned from existing open-source checkpoints, Lumen Sovereign will be built from scratch using proprietary datasets developed entirely in-house across pre-training, mid-training and post-training stages. Cosine will also apply novel training techniques to extend the model’s long-context and agentic workflow capabilities, particularly across software engineering and regulated enterprise operations.
Cosine CEO and co-founder Alistair Pullen said, “AI is the single most important technology of our generation. Enterprises are increasingly waking up to the risk of being wholly dependent on foreign providers for this technology. Vendor lock in creates security risk, dependency risk and cost escalation risks. Cosine is addressing those risks by building a model that is fully trained on UK soil and available into air gapped environments at a far more efficient price point than OpenAI and Anthropic alternatives.”
Emily Prince, group head of enterprise AI, LSEG, said: “AI adoption in regulated industries depends on trusted data, strong governance and secure deployment in the environments where institutions operate. This initiative aligns with LSEG’s AI strategy, making trusted AI available responsibly and at scale across the workflows our customers use every day.”
Graham Smith, head of AI, data science and innovation at NatWest Group: “The UK has strong foundations in AI, and this is an opportunity for us to help shape its future in a way that is responsible and focused on real customer needs. We’re prioritising using AI to improve how we serve customers and enhance how our colleagues work, and by collaborating with partners in the UK and overseas we can help develop AI that makes a real difference for customers and businesses across the UK.”
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