Donald Trump's shock victory over Hillary Clinton in an historic US presidential election is like a "second Brexit" that will increase economic uncertainty in the short term, Sir Martin Sorrell, the founder and chief executive of advertising giant WPP, has warned.

Sir Martin, whose wife Cristiana Falcone Sorrell gave birth on Election Day, admitted he was surprised by the result and said it will take a "significant amount of time to assess the implications" of the election result.

"Increased levels of uncertainty will mean more hesitation to make important decisions in the short term, both by people and governments. But it may accelerate implementation of helpful reforms in the medium term to reduce uncertainty and stimulate investment as a result," Sir Martin said.

"Clearly immigration, trade and terrorism were key issues that swayed electoral opinion in a very significant way, just as they did in the UK, and probably will in the European referenda and elections to come," he added.

The WPP chief concluded his reaction by saying that he felt there was "a lot of reassessment" still to come over polling techniques, which once again failed to predict the result.

"Electorates at times like these clearly don't like to be told how they're going to vote especially by the media and other elites," Sir Martin said.

US Election: New president Donald Trump in numbers

Sir Martin, named the second best performing chief executive in the world by the Harvard Business Review, warned last month that his company had seen the first signs of “Brexit anxiety” in the UK.

WPP, reported third-quarter revenues of £3.6bn, up 3.2 per cent compared with the previous year but down slightly from the 3.5 per cent growth rate in the second quarter.

Why we should all go to Canada Show all 8 1 /8 Why we should all go to Canada Why we should all go to Canada The great outdoors You might spot a moose, for goodness' sake Mark Rowland/Flickr Why we should all go to Canada Road trips You can drive through some of the most incredible scenery MaxGag/Flickr Why we should all go to Canada Maple syrup It's available in almost any form, including maple taffy - heated syrup that's been dropped on to ice to cool and turned into a kind of chewy lollypop Márcio Cabral de Moura/Flickr Why we should all go to Canada Friendly Cities The likes of Montreal, Vancouver and Toronto are not only cool, but welcoming too Getty Images Why we should all go to Canada Arctic cruises You can float between icebergs - enough said Shutterstock Why we should all go to Canada Skiing and snowboarding Resorts such as Whistler are world class Getty Images Why we should all go to Canada Real winter Canada really embraces the cold, with everything from igloo raves to husky rides EveryDamnNameIsInUse/Flickr Why we should all go to Canada Wine They make a pretty good tipple here Nomade Moderne/Flickr

In the UK, growth has slowed to 2.1 per cent in the third quarter from 3.5 per cent in the second quarter.