Some of Canada's top pension funds, among the world's biggest investors in British real estate and infrastructure, are holding back on UK deals until after Britons vote on whether to leave the European Union, according to senior executives. These funds, which together manage more than C$700 billion ($524 billion) in assets, fear valuations could drop if Britain chooses to leave the bloc and have particular concerns about the impact on London's financial district, the executives said. There is no precedent for an economy as big as Britain's leaving a trade bloc, and the rival campaigns paint contrasting pictures of what quitting the EU might mean for its trade. Pro-Europe campaigners say banks and other financial institutions could pull operations out of the City of London if they cannot access critical EU markets.