The church plant was started three years ago with a residence to provide housing and support for immigrants as they tried to establish themselves in Spain.
"Early on Ademir and Miriam, a Brazilian couple, moved in," Coralie said.
"They came to make money as they needed to repay debts in Brazil."
"Their marriage was struggling and they lived, along with Miriam's sister, in a small bedroom in the basement of the residence."
They began to learn Spanish and attend the church, having no other support around them.
"Ademir committed his life to the Lord, stopped drinking, and also committed himself to make his marriage work," Coralie said.
The transformation was dramatic.
"They became active members in the church as their faith grew and they also helped out with a new immigrant church plant in a low socio-economic area of Madrid."
"They shared their money, their time and their lives with those around them."
Miriam too experienced huge growth in her walk with God.
"The greatest thing Miriam realised during their time in Spain was that the Lord had brought her here to serve, not to make money."
Miriam and Ademir recently moved back to Brazil.
"We miss Ademir and Miriam but know that they have taken the light of Jesus back to their own people and home," Coralie said.
Immigration has exploded across Europe during the Prestons' eight years in Spain, with people from North Africa, Eastern Europe and Latin America seeking a better life.
"They come with dreams to gain material wealth so that they can bring the rest of their family over, or return with money."
However, many do not fulfil this dream and return to their homelands worse off.