Thousands of other British businesses and individuals would also be affected

The website of the pro-Brexit campaign group Leave.EU is likely to vanish from the internet in the event of a no-deal Brexit, as part of a move that will affect hundreds of thousands of other British businesses and individuals with .EU domain names.

There are about 340,000 registered British holders of these web addresses, and the government has urged them to make contingency plans as their web addresses will disappear if the UK does not agree a deal with Brussels.

The domains were introduced in 2006 as a rival to the likes of .com and .org but are available only to individuals or businesses based in the EU or the European Economic Area (EEA).

Ironically, possibly the highest-profile British user of such a domain is Leave.EU, the organisation founded by the Ukip donor Arron Banks. It became one of the leading pro-Brexit campaign groups in the 2016 referendum and has since been dogged by fines, police investigations and questions about its funding.

The Bristol-based Leave.EU, which built its online identity and corporate branding around its .EU domain name, is likely to lose control of its main website address and email accounts associated with the domain in a no-deal scenario.

“If we leave with no deal our job is done,” said Leave.EU’s communications chief, Andy Wigmore, who suggested he had a contingency plan. “No need for Leave.EU any more. Cheers all round, I’m sure!”

Leave.EU has transformed itself since the referendum into a campaign group against centrist Conservative MPs and it produces a relentless stream of aggressive content agitating for a hard no-deal Brexit.

Although Wigmore celebrated the potential removal of his own campaign’s web address, other businesses and individuals who use the domains may be less happy.

Updated government guidance confirms that if the UK leaves without a deal at the end of March then domain owners based in the UK will have two months leeway to move their principal location to somewhere within the EU or EEA.

“These .EU domain names will then be withdrawn and will become inoperable,” states the guidance issued by the Department for Digital, Culture, Media and Sport, which confirms warnings issued this year by the EU’s domain registrar. “This means you may not be able to access your .EU websites or email from 30 May 2019.”

After a year, all the British-registered .EU domains will be made available for purchase by individuals and companies who continue to reside in the EU. This raises the possibility that on the anniversary of a no-deal Brexit, one lucky German or Spaniard could be able to mark the occasion by taking over the Leave.EU domain and using it for their own purposes.