Since the European Commission covers trade negotiations on behalf of its member countries, there is an acute shortage of negotiators in London.

Tom Brake, the foreign affairs spokesman for the Liberal Democrats who campaigned to remain in the European Union, has so far failed to extract meaningful figures from the government about its consultancy spending, though he says that top trade experts charge up to $10,000 a day.

“I suspect the government is racking up phenomenal costs,” he said. “I am sure that the people who voted to leave, who had genuine grievances about the lack of job opportunities, did not envisage that one of the side effects of Brexit would be many jobs for highly powered legal and consulting firms.”

In one well publicized episode last year, Deloitte, the advisory company, apologized after a memo leaked by one of its employees suggested that the government had no plan for Brexit, estimating that up to 30,000 extra civil servants might be needed. After the leak, which infuriated ministers, Deloitte agreed not to bid for government contracts for six months, the British news media reported.

But where there is confusion there are opportunities. Most big advisory firms now offer Brexit advice, and smaller companies promote themselves as experts. One firm calls itself “Article 50 Associates,” named for the European Union treaty article that Britain will use to withdraw, and describes itself as “a specialist political consultancy focusing on helping individuals, enterprises, agencies and others navigate the twists and turns in the Brexit process.”

All this activity has started a race to hire what is known in the consultancy world as “Brexit talent.” Sometimes it almost seems as if the vote’s campaign teams, have largely transferred to the private sector, where former rivals often work side by side. And the vote’s outcome has not prevented some high-profile Remain campaigners from emerging as winners in the consultancy world.

Teneo, an advisory firm that has a “Brexit client transition unit,” has taken on Craig Oliver, Mr. Cameron’s former director of communications, as well as William Hague, a former British foreign secretary.