Why so shy, General Petraeus?

Former CIA director and US Army General David Petraeus is in town hosted by the Henry Jackson Society. But that’s classified.

For some reason Petraeus is being very shy in front of journalists (well, most journalists). The event in the House of Commons this afternoon is being held under the Chatham House Rule. All media, your humble correspondent included, have been refused entry. What was it about the affair with his biographer that led to his resignation as America’s top spook which the shy general does not want to be asked about?