Europe's flagship plan to open the channels for investor capital to flow across the single market could take on greater importance in the event of a Brexit – but the absence of a British voice in its development would be felt in both UK and the EU.

The Capital Markets Union is aimed at making it easier for companies to get access to funding from anywhere in the EU by reducing barriers to cross-border investment. The plan is being led by the EU's financial services commissioner Jonathan Hill, a UK Conservative politician.