In the middle of the night, four high-tech armored trucks left a secret facility accompanied by police and a helicopter flying overhead. Inside the trucks were an extremely valuable cargo—20 wooden boxes packed with gold bars. When they arrived at a London airport, the boxes were loaded and tied down in a Boeing 737 freight plane that flew to an airport in Poland. From there, the cargo was transported under full police escort in three armored vehicles to National Bank of Poland vaults in three different locations. 

This top-secret procedure was repeated eight times as Poland repatriated a total of 8,000 bars of gold, 100 metric tons in all, worth more than $5 billion.

The bars of gold were gradually moved from Bank of England vaults to a specially built gold storage facility just outside of London where they were counted and packaged. Each bar weighs 12.5 kilograms and is stamped with a serial number and marker to identify where it was produced. 

“The movements of the gold were meticulously planned in coordination with everyone, including the police, the Bank of England, the Narodwy Bank Polski (Polish National Bank) and G4Si,” said John Lennox of security firm G4S International Logistics (G4Si). The company described the transfer as one of the biggest private movements of gold between banks.

The operation brought gold back to Poland after the government had arranged for its entire reserves of gold to be evacuated just four days after Nazi Germany invaded the country at the beginning of World War II. On September 4, 1939, about 80 metric tons of gold was sent on a secret journey through Romania, Turkey, Africa, France, New York and London. Poland had stored gold in the vaults of the Bank of England, as many countries do, until, earlier this year, it made the decision to bring home more than 40 percent of its gold reserves.