Forget the Irish backstop – the biggest Brexit crisis is happening at another border altogether

Spain’s modern politicians regret the 1713 treaty that ceded Gibraltar to Britain, and they could use the years of post-Brexit negotiations to make life very difficult for the Rock

Today is Gibraltar’s national day. It marks the referendum date in 1967 when the Mediterranean territory voted by an overwhelming 12,138 to 44 to remain a British overseas territory. Another ballot in 2002 rejected Spanish sovereignty proposals by an equally crushing margin. Oh for referendums with such decisive majorities.

Half a century on, there’s a cloud on Gibraltar’s horizon: Brexit.

The self-governing territory joined the EU on the UK’s coat-tails in 1973 and now forms part of my constituency as an MEP. In 2016, Gibraltarians voted 96 per cent to remain in the EU; in the recent European elections, 77 per cent voted in support of the strongly anti-Brexit Liberal Democrats. It's not hard to see why.

Political, economic, social, trading and cultural relations between the Rock and the neighbouring Spanish region of the Campo de Gibraltar are a textbook example of two territories using EU rules to create mutual prosperity. One in four jobs in the Spanish region is supported by Gibraltar, while more than 14,000 people cross the border every day to work in the British territory. Almost half of Gibraltar’s jobs are taken by frontier workers and in some sectors, such as tourism, it’s more than 70 per cent. The tourists themselves take advantage of an open land border: in 2017, 9.8 million people used it to visit Gibraltar. And Gibraltar airport is also governed by EU civil aviation measures under the Single European Sky agreement (despite Spain’s objections).

A no-deal Brexit is the scariest scenario. Northern Ireland’s border issues are grabbing the headlines but Gibraltar is even more dependent on a fluid, open border. The close, mutually beneficial relationship between Gibraltar and its Spanish neighbours is at obvious risk from the uncertainty and expected border disruption of no-deal. The government’s own assessment predicts hours of delays for border workers, and the disruption of food, medicines and other goods due to extra checks – all of which will harm Gibraltar’s economy.

Even Theresa May’s managed Brexit deal conceded (despite many transitional arrangements being put in place) that “after the United Kingdom leaves the Union, no agreement between the EU and the UK may apply to the territory of Gibraltar without agreement between the Kingdom of Spain and the UK.” Spain’s modern politicians now regret the 1713 treaty that ceded Gibraltar to Britain in the first place. They could use the years of post-Brexit negotiations that lie ahead of us even in a soft Brexit to make life difficult for the Rock. The claim that Brexit uncertainty will all be over on 31 October even if Boris Johnson gets his way is, of course, a lie.

And just think what price Spain might extract for the return of the UK to the EU as a member state, if Brexit happens but our children later conclude that it was a ghastly, historic mistake. Spain followed the UK into the EU so has never before had the prospect of holding such an extraordinary bargaining chip. We would all hope that a future UK government’s commitment to self-determination would withstand any re-entry negotiations. But this wouldn’t be guaranteed.

Brexit doesn’t just pose an immediate threat to Gibraltar’s daily life and prosperity. If it happens, it will cast a very long shadow over the Rock and its future.

Martin Horwood is Liberal Democrat MEP for South West England and Gibraltar