Ed Miliband has said the revelations in the leaked Panama Papers provide evidence that wealth does not trickle down in society – rather, it gets “stashed”.

Speaking two weeks after the huge cache of documents were revealed, detailing the tax affairs of thousands of wealthy individuals worldwide, the former Labour leader said the leak proved the common assumption about capitalism to be false.

In an interview with the Observer, he said he understood why David Cameron defended his father after the Panama revelations were leaked. “But for 30 years, since Reagan and Thatcher, the basic view has been, ‘Be nice to the super-rich and their wealth will trickle down.’ That is the big lesson of Panama for me. It doesn’t trickle down; it gets stashed.”

The former Labour leader is helping to promote a new low-budget documentary, the Divide, which explores the wealth gap through seven families striving for a better life in Britain and the United States.

Speaking about the film, Mr Miliband added: “It shows the fabric of people’s lives. It’s the stress for the middle-class bloke as well as the insecurity for people in precarious jobs. It’s something I wrestled with as leader…how to show the impact.