When the government launched the Northern Powerhouse, the plan was to attract investment and improve the infrastructure. But four years on, some of the big projects have failed. These high-profile property developments were marketed with great fanfare, and some were promoted and backed by the local authority.Now building sites stand abandoned, local investors have lost millions and confidence in the north has been badly damaged. So what went wrong? Reporter Michelle Ackerley investigates why some projects have failed, as well as the local developers and businesses that made big promises but have failed to deliver.