Luke Coffey is Director of the Allison Center for Foreign Policy Studies at The Heritage Foundation. He previously served as a Special Adviser in the Ministry of Defence.

In June’s Brexit vote, the citizens of Gibraltar voted overwhelming with the “Remain” camp. The acting Spanish foreign minister Jose Manuel Garcia-Margallo quickly pounced, suggesting that the UK and Spain should agree to “joint sovereignty” over Gibraltar.

London swiftly rejected this suggestion. But simply ensuring that Gibraltar remains British is not enough. The Government must now take steps to safeguard the Rock’s interests during the UK’s Article 50 negotiations with the European Union (EU).

Many in Gibraltar feel anxious about the outcome of the Brexit vote. After all, 96 per cent of the Gibraltarians participating in the referendum voted to remain in the EU. Other than issue the obligatory statements from the Foreign Office, the Government has done little to reassure those living on the Rock that their interests will be safeguarded.

Currently, Gibraltar has a unique status inside the EU which might make leaving slightly easier for the Rock than for the rest of the UK. Even though it is part of the EU’s Single Market, it is not part of the Customs Union. Gibraltar is excluded from the EU’s Common Agriculture Policy, the Common Fisheries Policy, and the Common Commercial Policy. Gibraltar is not part of the Eurozone and or the Schengen Area. It is also excluded from the EU requirement to levy VAT.

How will Gibraltarians determine whether London has protected their interests during the Brexit negotiations?  The process will be deemed a success provided that:

1) Gibraltar remains wholly and completely British (for as long as its inhabitants want this);

2) Gibraltar retains its attractiveness to foreign investors by remaining a regional financial, shipping, high-tech, and tourism hub, and

3) Gibraltar maintains its current economic growth well into the future.  If the correct policies are pursued achieving these goals should not be a problem.

So how can the Government demonstrate its commitment to the Rock during the Brexit process?

First and foremost, Theresa May, Boris Johnson, Liam Fox, Michael Fallon, and David Davis should make a joint visit to Gibraltar as soon as possible. To show that this is an issue of national importance, members of the Shadow Cabinet and representatives from other political parties in Westminster should be invited to join as well. (Whether or not they do so is another matter.) The Ministry of Defence should also make a grand gesture by increasing the Royal Navy’s visible presence in Gibraltar.  This would send an important message to the Gibraltarians.

Secondly, the future of Gibraltar outside the EU should not be treated as a bilateral issue between the UK and Spain. This is what Spain wants. Instead, the post-Brexit status of the Rock must be addressed during the Article 50 negotiations with EU. While the status of Gibraltar is important to Spain, it is peripheral to the rest of the EU. It is unlikely that Brussels (or Berlin) will allow Spain to hijack the issue.

Thirdly, the new Department of Exiting the European Union should establish a Gibraltar Planning Unit dedicated solely to looking after Gibraltar-specific issues that will arise during the Article 50 talks.  This unit should include direct ministerial oversight, which could be done by appointing a Parliamentary Under-Secretary for Gibraltar working directly for the Brexit Secretary David Davis. Once Brexit occurs, the Gibraltar portfolio would move back into the Foreign Office. Also, the new Department for International Trade must also factor in Gibraltar as it starts scoping out free trade deals around the world

To make this work, officials from the Government of Gibraltar should be seconded to work in the Gibraltar Planning Unit to provide technical advice throughout the Brexit process.. Before anyone asks: no, a similar planning unit should not be established for Scotland. The constitutional relationship between Scotland and Westminster is completely different from Gibraltar’s as a British Overseas Territory.

Fourthly, the Gibraltar Planning Unit must be used to find sources of leverage against Spain to maximize the UK’s bargaining position during the Article 50 negotiations vis-à-vis Gibraltar. This might include influence the UK has in international organizations or fishing rights in the waters around the Falkland Islands or other British territorial waters.  Spain should also be reminded that as many as 13,000 Spaniards from Andalucía rely on employment in Gibraltar.  Currently Andalucía suffers the highest regional unemployment rate (32 percent) in the EU. Spain should not cut its nose to spite its face by closing or tinkering with the land border.

Finally, in the event that the EU caves to Spain’s anachronistic behavior toward Gibraltar, the UK needs to prepare for the worse. This could include maintaining a robust air bridge if the land border is closed. Also, in the event of a border closure by Spain, the UK must be prepared to respond with appropriate, firm, and proportionate measures against Madrid.  It must be made crystal clear to Spain that there will be a cost to pay for reckless behavior.

Gibraltarians are tough – it is in their DNA. Since 1309, the Rock’s inhabitants have endured 14 sieges. In 1969, Franco closed the land border cutting off the Rock from the rest of Europe until 1985. This divided families and hurt the economy, yet the people of Gibraltar never wavered.

Fabian Picardo, Gibraltar’s Chief Minister, told the Rock’s parliament the day after the referendum that: “Gibraltar will never pay a sovereignty price for access to a market. Gibraltar will never be Spanish in whole, in part or at all.”

Gibraltarians revere sovereignty and self-determination perhaps more than any other people in the world. Westminster has a moral obligation to protect the interests of British citizens living in Gibraltar as they would if they were living in London, Cardiff, Belfast, or Edinburgh.

If the right policies are pursued, and the UK enters the Article 50 negotiations with a plan, this should not be a problem.