The Tory leadership contest has propelled a piece of Brexit jargon into the national conversation – Gatt 24.

– But what does it mean?

The General Agreement on Tariffs and Trade (Gatt) is a post-Second World War legal agreement that forms the basis for the trade in goods around the world today.

It was replaced by the World Trade Organisation (WTO) in the 1990s, although the original Gatt text is still in use.

If Britain leaves the EU without a deal then trade would have to take place in line with WTO rules – and their associated tariffs.

Article 24 allows for the creation of an interim agreement necessary for the formation of a customs union or a free-trade area, which could stay in place for up to 10 years. International Trade Secretary Liam Fox has dismissed Bris Johnson’s claims on Gatt 24 (Stefan Rousseau/PA)

– Can Gatt 24 be used for Brext?

Boris Johnson has insisted Gatt 24 offers a possible “way forward” with “agreement on both sides”.

However, International Trade Secretary Liam Fox, a Brexiteer who is backing Jeremy Hunt for the Tory leadership, warned Brussels has made clear no such agreement would be forthcoming.

Even if the UK and EU agreed to pursue Gatt 24, other WTO members could veto it.

According to the House of Commons Library, the possibility of rejection has proven to be enough of a deterrent that no WTO members have notified an interim agreement since 1995.

And, against all this, Gatt 24 only applies to the trade in goods.

According to figures, services accounted for 40% of the UK’s exports to the EU in 2017. A separate agreement under the WTO’s General Agreement on Trade in Services (GATS) would be needed for that.

Finally, such a move would be unusual to say the least, because it is the reverse of a normal Gatt 24 application.

WTO expert Peter Ungphakorn explained in a blog post: “The UK and EU have a single market arrangement and are withdrawing some or all of its features. Here the notification will be needed almost at the start of the negotiations, not at the end.

“Knowing the final destination so early in the process might not be so easy.”

- Press Association