Companies’ confidence in Britain’s financial prospects has fallen to the lowest level since early 2013, hit by uncertainty over the possibility of Brexit and concerns about global growth, a survey of marketing executives found. But the IPA Bellwether survey published on Thursday showed that companies raised their marketing budgets marginally in the first quarter, with 23.3 percent of respondents forecasting a higher spend over the next 12 months. During the first three months of the year when the 300 British marketing professionals were questioned, Britain’s Prime Minister David Cameron agreed a new deal with EU leaders and set June 23 as the date for a vote on European Union membership. The report’s author said uncertainty about the referendum, plus concerns about a weaker rate of global growth, dented executives’ views of prospects for their sectors. The number of executives who were pessimistic in the first quarter compared to three months ago exceeded those who were optimistic by 6.5 percent, a reversal of the 7 percent lead held by the optimists in the previous period. The IPA Bellwether also forecast that advertising spending would grow 3.3 percent in 2016, a downgrade to a forecast of 3.9 percent growth made in the fourth quarter. Paul Bainsfair, Director General of the IPA advertising, marketing and communications body, said the next quarterly survey would probably present a clearer picture. “Following the referendum in June, the summer Bellwether should hopefully provide better clarity on where we are headed,” he said in a statement. “On balance, some growth seems the most likely outcome especially with the European football championships and Olympics set to provide a shot in the arm to budgets in the immediate months ahead.” A separate report by the Internet Advertising Bureau (IAB) published on Thursday said spending on digital advertising grew 16.4 percent in Britain in 2015, up 16.4 percent from 2014, representing the fastest growth rate for seven years. The IAB said smartphones were the driving force behind the pick-up in growth, with spending on mobile rising 60 percent to 2.63 billion pounds ($3.7 billion), accounting for 30.5 percent of all digital advertising.