As foreign AI tools hit legal and security barriers across defense and critical infrastructure, a homegrown British lab steps in — with government backing to match.
The UK government has selected Cosine, the British AI company whose models have outperformed those of OpenAI, Anthropic, Mistral and DeepSeek on independent coding benchmarks for two consecutive years, as one of the first partners in its newly launched £500 million Sovereign AI program.
Cosine was founded in 2022 by Alistair Pullen — who has been building AI products since 2018 and shipped his first iOS app at the age of nine — and Yang Li, who previously scaled bike-sharing platform Mobike to 220 million users across four continents before its $55 billion acquisition. A Y Combinator graduate, the company has raised $8 million from investors including Lakestar, SOMA Capital and Gaingels.
Operating as both an AI laboratory and a product company, Cosine builds and owns its models, trains its agents and deploys the full technology stack. Its platform supports more than 38 programming languages — among them Fortran, COBOL, Ada and Verilog — purpose-built for the legacy codebases that underpin Britain’s defense systems, nuclear infrastructure and financial services sector.
It is the only end-to-end sovereign AI coding platform built, owned and operated entirely in Britain.
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Cosine is already engaged with UK defense prime contractors and critical national infrastructure operators, including organizations involved in Britain’s nuclear deterrent program and next-generation defense platforms. For organizations operating at the classified edge of British industry, transmitting code to a foreign-managed server is frequently prohibited on legal and operational grounds. Cosine was built for precisely that constraint: its platform deploys entirely within a customer’s own infrastructure, with no internet connection, no data leaving the building and no reliance on foreign-managed models.
Through the UK’s AI Research Resource (AIRR), the Sovereign AI Fund has awarded Cosine 500,000 GPU hours on Isambard-AI — one of Europe’s most powerful supercomputers — representing millions of pounds in infrastructure value.
For the first time, this makes it possible to build and deploy a fully sovereign AI model entirely on British soil, with no foreign dependency at any stage. The Sovereign AI Fund’s venture arm has also secured the option to participate in Cosine’s next funding round.
“Cursor and Claude Code are outstanding products. They are also legally off the table for a lot of our customers,” said Alistair Pullen, chief executive and co-founder of Cosine.
“The moment your work touches classified infrastructure, you need an AI that lives entirely inside your walls. We built Cosine that way from the start, because retrofitting security onto a cloud product is not the same thing — and the people we work with know the difference. What we are building now goes further: a truly British AI laboratory, producing sovereign models for Britain’s most critical use cases, owned and controlled by the UK, for the benefit of the UK.”
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Yang Li, chief operating officer and co-founder, added: “For two years we have been telling defense primes and critical infrastructure operators that we can do what no one else can: air-gapped, on-premise deployment, trained on the legacy code that runs Britain’s most sensitive systems.
“The one thing we could not say was that the model itself was trained on sovereign infrastructure. The AIRR grant completes that picture. The UK should be an AI maker, not an AI taker — and this is what that looks like in practice.”
