Sometimes it's good to watch little dramas unfold in the natural world.
At this time of year male Swans (Cobs) get rather territorial and protective of their ladies (Pens). So if another pair, or this time a pair plus one youngster intrude to close the male will defend his patch (sound familiar?)
The first sign that this one was getting his dander up was when he raised his wings in the start of a threat posture.
Once he really got going he started to run across the water, flapping vigorously and making a charge at his perceived rival.
The other guy didn't seen too interested and made a rapid exit to what seemed to be a safe distance.
Once the job was done, it was chest out, head up and back to show of to the love he had just defended.