The EU is negotiating its own agreement with the US, the Transatlantic Trade and Investment Partnership

It will, according to President Trump, be very big, very powerful and very quick. But would a trade deal with the world’s largest economy live up to its billing?

Liam Fox, the trade secretary, says his department estimates that it would raise trade between the two nations by £40 billion by 2030 — or about 25 per cent. Not all of that would translate into economic growth because much of it may merely be displacing trade with other countries.

The EU is negotiating its own agreement with the US, called the Transatlantic Trade and Investment Partnership. The government previously estimated that that could eventually raise GDP by £10 billion.

Yet most estimates suggest that an American deal would not come close to plugging the shortfall