BA is running a Business class sale in the US for two days right now. It's $2010 from most cities in the US to Europe. Non-Profit AARP offers $400 off on Business class or higher fares using their portal. Then if you use 30k avios you get another $800 off. That and the fact that the IAD to LHR fare was actually starting at less than the $2010 sale made the final ticket price out at $449 cash out of pocket.