It is not surprising that these angers have arisen. Obama and Cameron are both pretty strong ideological leaders, and as a result, people who aren't your normal activist groups are reacting against them with fear and anger. In America, the Tea Party influence in Washington has everyday liberals needing to express their feelings of anger and fear that all that they have worked for so many decades to build could be torn down overnight by their enemies. It is the same response that so many unsophisticated conservatives had watching Obama and the liberals in Washington tear down everything the conservatives had built since Reagan.
Both feel like the world that they know and love is being destroyed by their enemies, that they are moving into a world that they don't know or believe in, and that they don't belong or fit in, or even want to be a part of.
The times, they are a changing...and both sides of the political spectrum are afraid, angry, and need to vent.