It was the voice of business that helped keep Britain in the EU bloc in 1975, the last time a referendum on the issue was held. Prime Minister David Cameron is hoping that the business community will rally round again and back his bid to keep Britain in a reformed EU. But the landscape is very different this time around: the business community is divided and support for a "Brexit" is rising.
Our UK correspondents travelled to Coventry, Birmingham and London to ask leaders of small, medium and large companies what impact they believe a "Brexit" would have on their businesses and on the wider economy.
A programme prepared by Yong Chim and Laura Burloux