Princess Diana would be furious with Prince Harry for leaving his brother William to pursue her charity work alone, an expert has claimed. RadarOnline.com can reveal William, 42, is set to appear in a new documentary highlighting the homelessness issues in the UK, a cause close to his late mom’s heart. In the build up to the screening, William mentioned Harry, 40, by name for the first time in several years telling tales of when Diana took them both as young boys to a homeless shelter in London. The reference of Harry was seen as an “olive branch” between the two warring brothers but according…