Sir Martin Sorrell has said today current levels of uncertainty are hurting businesses, but Brexit was far from the only problem.
Speaking at the Confederation of British Industry annual conference, the WPP group chief executive said of the Brexit negotiations: "What business wants is more certainty but, given the different objectives of both parties (businesses and government), that's where we are."
Sorrell, whose company's staff within the UK is made up of roughly 15 per cent EU nationals and had flown in to London from Madrid from the conference, said he was "extremely worried" about what clamp downs on immigration following Brexit would mean for business.
However, he also noted that, while Italy's economy was presently a strong player, that could quickly crumble because of the upcoming referendum in the country and the bank crisis facing the nation's lenders.
He also noted that France's impending elections, particularly following last night's bowing out of former President Nicolas Sarkozy and the rise in popularity of the far-right National Front's Marine Le Pen, could also create more problems for anybody trying to do business across Europe.
However, on the subject of new President-elect Donald Trump, Sorrell said businesses were likely in wait and see mode.
"The honest truth is we don't know which Donald we're going to see," he added, but he also noted that Trump would be "good for the markets in the short- to medium-term".
The industry veteran, whose pay packet usually comes among the top of FTSE 100 chief executives, pushed back at suggestions his company was a corporate governance failure, noting that his business had seen incredible growth.
However, he voiced concerns that short term goals, such as quarterly accounting expectations, were being treated as the be all and end all of measuring a business' worth. He remarked that the likes of Amazon, which tend to be more focused on the long-term, are, as a result, now giving many other firms a run for their money.
Sorrell added that one of his biggest worries was "the short term focus of clients".