Blue-sky exercise envisages four levels of membership to allow for countries having looser ties to the union

A vision of a future EU with four types of membership – including an “EU lite” for countries such as the UK – has been tabled by a group of academics commissioned by France and Germany to consider future reforms.

The proposal comes as the UK’s opposition leader, Keir Starmer, told France’s president, Emmanuel Macron, that he wanted to build an “even stronger” relationship between the two countries if he wins power at a national election pencilled in for next year.