When Andrew McConnell won the Luis Valtuena Humanitarian Photography Award he was given a grant to document the activities of Spanish NGO Medicos del Mundo. “They offered me a choice of the many projects they work on around the globe, and I chose Western Sahara, because it was an area I was always interested in,” says the Irishman, who abandoned press photography seven years ago to concentrate on longer-term projects.

Sovereignty of the country has been disputed since Spain withdrew in the last days of Franco. Morocco annexed the territory, the native Saharawi people, through the Polisario Front, fought for their independence and the country was split down the middle. A ceasefire was agreed in 1991, with a promise of a self-determination referendum to follow. The ceasefire holds but the referendum has yet to happen.

“I think the Polisario would be happy to resume fighting,” says McConnell, “but their weapons are old and they can no longer rely on the support of Algeria to resupply them. In the passing years the Moroccans have invested massively in their military.” The most obvious manifestation of this investment is the construction of a giant 1600km-long wall of sand, a heavily-mined barrier splitting the country in two.

To get his story McConnell first flew to Algeria and then travelled to the refugee camps, home to some 170,000 Saharawis. “I travelled to stay with Bedouin Saharawis in what they call the ‘Liberated Territory’ [conversely the Moroccans control the ‘Occupied Territory’]. Here, a member of the Polisario took me up close to the sandwall. There are heavily fortified watch towers every 200 metres or so and we could see Moroccan soldiers guarding this internal border.”

To get his shots for the series, The Last Colony, McConnell used continuous LED lighting, which allowed him full control over illumination. “I also got used to using the light of the moon. Shooting at night under a full moon would mean exposures of 10 seconds, and with a half moon perhaps 20. No moon, no night shots, so I would work at dawn and dusk.”

McConnell is no impartial observer, and sides with the Saharawis. He later flew to Morocco. “The Moroccans have strict media control and are very suspicious of visiting journalists and photographers, so my trip had to be covert. I travelled to the town of Smara near the wall but I had barely checked into my hotel when I realised I was being watched, so I could not make contact with Saharawis living there. Two men, obviously undercover police followed me for two days and all the way back to the airport.”