Flextension, Yellowhammer, the tunnel and Norway option: Key Brexit terms explained

The UK's decision to leave the European Union has thrown up a number of new terms of phrases not typically used in common every language.

Some of the words and terms are entirely new, so here's a look at some of the new jargon which has entered the British language lexicon.


As the EU voted to delay the UK's exit from Brussels until January 2020, Brussels has offered a flexible extension to Article 50 for a maximum of three months, if needed.

The UK would be able to leave earlier than that January 31, 2020 deadline if the Withdrawal Agreement Bill can be ratified by MPs and MEPs in time.

The UK could officially quit the group on either November 30, or December 31, if the two parliamentary bodies can agree in time.


Brexit is the UK's withdrawal from the European Union.

The term was added to the Oxford English Dictionary on December 2016 and means "the (proposed) withdrawal of the United Kingdom from the European Union, and the political process associated with it”.

The Norway option

Some supporters of a “soft Brexit” argue that the UK should take its lead from the members of the European Free Trade Association (Efta) – Iceland, Liechtenstein, Norway and Switzerland – and seek a close relationship with the EU short of full membership.

As a member of the European Economic Area (EEA), Norway enjoys full access to the internal market for most trade in goods, but must implement the bulk of Brussels regulations without having a say in its decisions. It also pays substantial sums into the EU budget.

The Norway options is a softer Brexit hich would see a close relations just short of full EU membership.

The Irish border

During the Brexit debate, the Irish border has been spoken about as one of the key issues which have complicated the UK's departure from the EU.

The border between the Republic of Ireland and Northern Ireland remains an issue as the Republic is an EU member state and there are currently no border checks between the two countries.

There are almost 300 crossings between the two countries along the 310-mile border.

During the Troubles, it was a heavily-militarised frontier and both sides want to avoid a return to a hard-border.

Hard border and soft border

A hard border would entail checks, while a soft would allow the border to operate as it does now.

The establishment of the European Single Market in 1993 and the Good Friday Agreement in 1998 means the border between the two countries is almost invisible.

It has been suggested that technology may solve the issue of cross-border trade, ensuring a soft border remains, which would avoid checkpoints which are likely to be required if it reverted to a hard border.


The backstop was an insurance policy in Theresa May's Brexit deal which would mean the Irish border would remain as it is if no wider trade deal was agreed by the UK or EU in the second round of negotiations.

Under the deal agreed between Prime Minister Boris Johnson and Brussels earlier this month, Northern Ireland will remain aligned with single market regulations on goods.

The UK will leave the EU customs union, as will Northern Ireland.

The region will remain an entry point into the EU’s customs zone.

UK authorities will apply UK tariffs to products entering Northern Ireland as long as they are not destined for onward transportation across the border.

EU rules on Value Added Tax and excise duties will apply in Northern Ireland, with the UK responsible for their collection. However, revenues derived will be retained by the UK.

The DUP has strongly objected to the terms of the PM’s deal.


The Prime Minister has an EU “Sherpa” – UK chief negotiator David Frost.

Also sometimes described as an envoy, he is Mr Johnson’s Europe adviser who holds talks with Brussels officials.

The Prime Minister has an EU 'Sherpa' – UK chief negotiator David Frost (stock image).

Article 50

A treaty in the EU which allows members to leave.

After they have notified the European Council of their intensions, the EU

After that, the EU “shall negotiate and conclude an agreement with that state, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the Union”.

The formal process to leave the European Union started when Mrs May triggered Article 50 on March 29 2017.

Customs union

A customs union is a group of countries which abolish import tariffs and quotas on goods traded among themselves.

Members of the union commit to observe a common external tariff, so that goods coming from outside the area pay the same duties, regardless of where they enter the bloc.

Labour has said it will try to amend the Withdrawal Agreement Bill (WAB) to ensure that the UK has to form a customs union with the EU.

The tunnel

The tunnel is Brussels jargon for secretive and intense talks among negotiators.

The Irish Times reported that, when a journalist asked a European Commission official where the tunnel was, they replied: “The tunnel is not a place, but a state of mind.”

The tunnel is EU jargon for intense and private negotiations.

Single market

The single market is described by the European Commission as one territory without any internal borders or other regulatory obstacles to the free movement of goods and services”.

The aim is to create competition and cut prices, remove barriers to trade, such as tariffs on imported goods.

The single market covers all members of the European Economic Area – 28 EU states as well as Iceland, Liechtenstein and Norway.

No-deal Brexit

A no-deal break means Britain would immediately cease to be an EU member state and would leave the bloc without a formal agreement in place.

Overnight, the UK would cease to be part of the single market and customs union.


Yellowhammer is a codename used by the Government relating to no-deal planning.

The Operation Yellowhammer document about a no-deal Brexit claimed to outline the Government’s “reasonable worst-case planning assumptions”.

Operation Yellowhammer is the government's preparation for a no-deal Brexit.

WTO rules

Should the UK leave without a deal, the legal basis for the free movement of goods between Britain and the EU would disappear and instead the UK would have to abide by World Trade Organisation (WTO) rules.

This would mean a new tariff regime as well as new customs and regulatory checks.

European Research Group

The European Research Group, or ERG, is a group of Conservatives defined by their strong Eurosceptism and formerly led by Jacob Rees-Mogg.

The holy grail for some Eurosceptics was an ambitious Canada-style free trade agreement with the EU, removing tariffs from almost all imports and exports of goods, offering co-operation on standards and allowing mutual recognition of professional qualifications.

A Canada-style agreement would allow the UK to leave the EU institutions, end freedom of movement and strike new trade deals elsewhere in the world.

Brexiteer and Remainer

A Brexiteer is someone who is in favour of the UK leaving the EU, while a Remainer is a word to describe someone who is in favour of the UK staying in the EU.