The UK government has selected Cosine, the British AI company whose models have outperformedOpenAI, 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 programme.
Cosine was founded in 2022 by Alistair Pullen — who has been building AI products since 2018 and shipped his first iOS app at age nine — and Yang Li, who previously scaled 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.
As both an AI lab and a product company, Cosine builds and owns its models, trains its agents, and deploys the full stack. Its platform supports more than 38 programming languages, including Fortran, COBOL, Ada, and Verilog — purpose-built for the legacy codebases that underpin Britain’s defence systems, nuclear infrastructure, and financial services backbone.
It is the only end-to-end sovereign AI coding platform built, owned, and operated entirely in Britain.
Cosine is already engaged across UK defence primes and critical national infrastructure operators, including organisations involved in the UK’s nuclear deterrent programmes and next-generation defence platforms. For organisations operating at the classified edge of British industry, sending code to a foreign-managed server is often legally and operationally prohibited. Cosine was built for that constraint: its platform deploys entirely within a customer’s own infrastructure, without an internet connection, without data leaving the building, and without 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 the most powerful supercomputers in Europe — worth 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. In addition, the Sovereign AI Fund’s venture arm has 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, CEO 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 lab, producing sovereign models for Britain’s most critical use cases, owned and controlled by the UK, for the benefit of the UK.”
“For two years we’ve been telling defence primes and critical infrastructure operators that we can do what no one else can: air-gapped, on-premise, trained on the legacy code that runs Britain’s most sensitive systems,” said Yang Li, COO and co-founder.
“The one thing we couldn’t 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.”