GIBRALTAR(AFP) - It's early morning and the sun shines down on a line of cars in southern Spain waiting to cross into Britain... or rather its overseas territory Gibraltar where a potential Brexit has set alarm bells clanging.
Miles away from the debate gripping Britain over whether to leave or stay in the European Union, this rocky outcrop of 33,000 residents where fish and chips and double-decker buses are a fixture is nevertheless eyeing June's upcoming referendum with increasing alarm.
At stakes are a thriving services-based economy that relies in large part on access to the EU's single market, and a sovereignty spat with Spain it believes threatens its only land access to the continent.
"I'm very concerned that it would mean that our current economic model would not be sustainable," says Gibraltar's Chief Minister Fabian Picardo, sitting in a white government building in the city centre.
The territory - half the size of London's smallest borough of Kensington and Chelsea - relies on tourism, financial services, online gaming and shipping services for its economy, which grew an estimated 10.3 per cent in the last financial year.
Part of the attraction for foreign investors lies in its low-tax regime. But Gibraltar's EU membership also allows firms approved to operate there to do business in any other nation of the bloc without having to re-apply for permission.
The combination has proved attractive to investment, insurance firms and others in the financial services sector, which represents around 20 per cent of Gibraltar's economy.
"One of the reasons why companies are here is their ability to sell their services throughout the EU... and that reason for being in Gibraltar will be taken away," says Picardo.
Not far from his government building, crowds throng a main street lined with shops, including the quintessentially British Marks & Spencer.
Nearby, tourists take pictures at a red phone box, just some of the millions who visit every year to get a taste of this seaside, sun-baked corner of Britain.
A large majority of visitors come across the small land border - a long-time flashpoint in the row between Gibraltar and Spain, which has wanted the Rock back ever since it had to cede the territory to Britain in 1713.
Spain's dictator Francisco Franco went as far as closing the crossing in 1969, all but stranding inhabitants who had to rely on air and boat links until it was fully re-opened in 1985.
Relations have ebbed and flowed since, but the past four years have seen a regain in tension under Spain's conservative government, which apart from sovereignty claims, also bristles at tobacco smuggling across the border and accuses Gibraltar of being a corporate tax haven.
In one particularly belligerent row over disputed waters, Spanish authorities upped border checks in 2013, creating hours-long logjams and forcing the European Commission to wade in and ease the crisis.
Many fear this could happen again if Gibraltar loses its EU status.
"Half or more of the clients we have are people who cross the frontier," says Isaac Batista, who works at a liquor store on the main street, where cigarettes and alcohol are far cheaper than in Spain.
"If the border closes, it's going to be very different," he adds, not just for retailers but also for the 10,000 people who make the crossing daily from Spain to work.
People like Manuel Marquez, an employee at a factory in Gibraltar's port who rides his scooter to the Rock every day from the border town of La Linea de la Concepcion with his wife Maria-Carmen, a cleaner.
The 57-year-old recalls how he sometimes had to wait up to nine hours to go home after a full day's work during the 2013 logjams.
His exasperation boiled over into protests and cost him two separate fines.
"I was desperate... We were thousands of people working here, suffering," he says, sitting at a fast-food joint on the Spanish side of the frontier - Gibraltar's large rock ever present in the background.
The spectre of Franco's border closure also hangs over many families who are divided between Spain and Gibraltar.
At the time, Marquez lived in the Rock. When he found out his father had died, he tried to cross via the sea, failed and jumped the border fence instead.
"I just didn't know what to do," he explains.
He was promptly detained by Spanish police, who allowed him to go see his family before sending him back to Gibraltar via Morocco.
But for Juan Franco, Mayor of La Linea, the real concern would be Brexit's impact on Gibraltar's economy.
Unemployment in his 72,000-strong city stands at 40 per cent, one of the worst-hit places in Spain, and the majority of those who work do so over the border.
"If Gibraltar stopped to generate work, it would be a real problem for our city," he says.