The world's most successful advertising exec thinks Hillary Clinton will become US president in 2016

Sir Martin Sorrell, the CEO of the world's biggest advertising agency holding group WPP, has predicted that Hillary Clinton will win the race to become president of the United States in 2016.

Clinton is leading the Democrat polls, according to USA Today's poll tracker, which is powered by Real Clear Politics. Just over half (56.3%) of Democrat supporters polled said they will vote for Clinton, compared to the 30.6% who said they would be backing the next most popular candidate, Bernie Sanders.

Writing for The Drum, Sorrell said: "I believe Hillary Clinton will emerge as the first female president of the United States."

He then went on to discuss how the result of the US election might affect the ad market and WPP. He thinks it will have only a little impact:

We don't benefit that much directly from political advertising, but it does stimulate the media market, and that will add a little more growth. I think the US will continue to be good for us. The question is what impact the Fed's decision on interest rates will have - the American recovery is there but it's more fragile than people think.

Among his other political predictions for 2016, Sorrell believes that the next Conservative Party leader in the UK will be hinged on the referendum on Britain's exit from the from the European Union.

If the UK votes for the "Brexit," then he thinks current home secretary Theresa May or even Mayor of London Boris Johnson might step up to become the next leader of the Tories. If the UK votes to stay in, Sorrell guesses that the chancellor of the exchequer George Osborne will succeed David Cameron instead.