Britain and the United States have signed a landmark technology pact aimed at boosting cooperation in artificial intelligence, quantum computing, and civil nuclear energy, alongside pledges of £31 billion ($42 billion) in investments from leading U.S. tech firms.

The “Tech Prosperity Deal” was announced during U.S. President Donald Trump’s state visit to Britain, which includes a ceremonial welcome at Windsor Castle hosted by King Charles on Wednesday.

According to the British government, the agreement will support joint AI development for healthcare, expand quantum capabilities, and streamline civil nuclear projects, with the goal of driving economic growth, scientific innovation, and energy security in both countries.

Prime Minister Keir Starmer described the deal as a turning point for Britain’s economic prospects. “This agreement has the potential to shape the future of millions of people on both sides of the Atlantic, and deliver growth and security,” he said.

The U.S. remains Britain’s largest single-country trading partner, and its technology giants have already invested heavily in the UK. Starmer, under pressure to revive a sluggish economy, has sought to position Britain as a hub for global investment by embracing the lighter regulatory approach favored by Washington, in contrast to the stricter European Union framework.

Among the headline commitments, Nvidia announced it will deploy 120,000 graphics processing units across the UK, its largest European rollout, including up to 60,000 Grace Blackwell Ultra chips through a partnership with UK-based Nscale. The collaboration will support OpenAI’s Stargate project and help establish Britain’s largest AI supercomputer.

Microsoft pledged £22 billion to expand its cloud and AI infrastructure, including a new supercomputing facility in Loughton, north-east London. Company CEO Satya Nadella said Microsoft aimed to ensure America remained a “trusted and reliable tech partner” for Britain, while President Brad Smith noted that relations had “hugely improved” since UK regulators dropped their opposition to the Activision Blizzard acquisition.