In 2017, Ms. Powell and Mr. Edelstyn set up a printing press in a disused bank branch to print their own money and sell the bills as works of art. They used 20,000 pounds, or about $25,000, of the proceeds to purchase £1.2 million of debt on the secondary market , where lenders sell bad debts to collections agencies, often for a small fraction of the original cost.

The purchased debt, mostly from short-term payday loans, was canceled, so the borrowers no longer had to pay it back. The explosion of the van, which contained the symbolically stamped slips of paper, was an artistic representation of the campaign.

The idea for the project came after Mr. Edelstyn met members of Strike Debt, an offshoot of the Occupy Wall Street movement, on a video shoot in the United States in 2013. “We were the last people you would ever describe as activists,” Mr. Edelstyn said of himself and Ms. Powell. But Strike Debt had “a totally fresh way of looking at economics,” he added. “I became obsessed.