Four years ago, I found myself in a beatdown apartment on the sixth floor of a tower block on the outskirts of Barcelona. The kitchen had been gutted, there was no running water and the less said about the bathroom the better. Some months before, the apartment had been repossessed by Blackstone, the US private equity giant that acquired tens of thousands of mortgages in Barcelona during the financial crash. The residents had been evicted and the property promptly put on the market. It was a familiar tale. The sheer scale of repossessions in the region had removed any hint…