Kellner, who is 68, with glasses and receding white hair, gave me another example of the way in which polling influences politics when I met him at YouGov’s offices near Old Street in east London, before Christmas. In the summer of 2013, when it became apparent that President Bashar Al Assad of Syria had used chemical weapons against his own people, Barack Obama asked David Cameron to support a U.S. attack against the Syrian regime. Parliament was recalled on August 29 to debate the proposal. Three days before the Commons vote, Kellner added a question to a YouGov poll asking whether people would support or oppose Britain’s participation in a military campaign. Fifty percent of respondents were opposed to British planes enforcing a no-fly zone over Syria or, if necessary, joining in the conflict.

The Sun published the results on a Wed­nesday. “That poll went round the world,” Kellner said as we sat in his office, a small, glass-walled cell in the corner of a much larger (and entirely empty) room. “It was the only poll ahead of the Thursday debate, in which it was accepted as a non-contentious fact that the public did not want the British government to take part in the operation.”

The government’s motion asking for MPs’ support for military action was defeated by 13 votes. “The Commons voted against, and Obama pulled back,” Kellner said. “So the Commons vote prevented, indirectly, the air strikes going ahead.

“Here’s the question I ask myself: Was our poll a key part of the chain that led to the attacks not taking place—and if it was, is that improper?” His answer is no.