Britain could become an “associate” member of the North American Free Trade Area after it leaves the European Union, it has emerged.

The plan was first proposed nearly 20 years ago by US senator Newt Gingrich, who is now tipped to be President-elect Donald Trump’s secretary of state.

Conservative MPs are backing the idea as a way of ensuring that Britain makes the most of opportunities after it leaves the EU, which is currently likely to be March 2019.