Anthropic has retained Charlesbye, the lobbying firm run by Boris Johnson's former communications director Lee Cain, as it kicks off the roadshow for an initial public offering targeting a valuation near $1.33 trillion.

The company appears for the first time in Charlesbye's U.K. lobbyist registry filing for the most recent quarter, according to Bloomberg. Cain declined to comment. The hire extends a run of British political insiders joining Anthropic while calls grow for tighter AI rules.

What does the hiring spree change for practitioners?

Anthropic has assembled an unusual concentration of former U.K. government talent at the exact moment Westminster has yet to legislate on AI. The roster now includes:

• Rishi Sunak, the former prime minister, who became a senior adviser after leaving office in 2024
• Liam Booth-Smith, Sunak's former chief of staff, who runs Anthropic's policy work across Europe
• Matt Clifford, who advised Sunak's successor on AI and joined in September
• At least nine other people from the Treasury and the government's technology and Cabinet offices, according to LinkedIn profiles cited by Bloomberg

For rivals and policymakers, the practical consequence is access. Anthropic met U.K. government officials 11 times in the first half of the year, against five meetings for OpenAI, according to filings from four departments.

An Anthropic spokesperson said the company backs the U.K. government's push to assess and address both the upsides and the hazards of AI. The company declined to comment on the Charlesbye contract or to give a count of its hires from government. The spokesperson said Sunak and Booth-Smith do not take part in "any lobbying of the U.K. government."

Booth-Smith told a U.K. parliamentary committee last month: "We have consistently believed that there should be binding rules on companies and that voluntary commitments are not enough." That statement positions Anthropic to the side of regulators rather than against them — a stance that could shape how any eventual U.K. AI statute treats frontier model builders.

Why does the timing matter?

The regulatory picture in Britain remains unresolved. The ruling Labour Party vowed in its election manifesto to introduce "binding regulation" for those building AI models, yet no law has followed. Anthropic is hiring political operators into that vacuum while it courts public-market investors.

The IPO adds financial urgency. Anthropic launched its roadshow on Tuesday with an expected price range of $70 to $78 a share, and has applied to list its Class A stock on the Nasdaq Global Select Market under the symbol "ANT," according to The Wall Street Journal. A $1.33 trillion valuation would place the company among the largest public listings on record, and regulatory risk in a major market like the U.K. sits squarely in the prospectus.

Anthropic has also built lobbying capacity on the American side of the Atlantic. Earlier this year, after the Pentagon labeled the company a supply chain risk, it retained Ballard Partners, a U.S. lobbying firm, according to Bloomberg.

The pattern tells practitioners two things. First, Anthropic treats government relations as a core function, staffed at senior level on both continents, not an afterthought. Second, the revolving door between Whitehall and the AI sector is now measured in double digits at a single company — a concentration that lawmakers scrutinising AI governance will likely note as the Labour manifesto commitment waits for a bill.