The notice a few metres away says

PLEASE DON'T FEED THE WATERFOWL
While it may seem a generous act regular feeding of bread and other foods not natural to the birds diet can cause
Malnutrition  
Aggressive behaviour
Spread of disease
Increased vermin in the area
Pollution to the water course
Overcrowding
KEEP WILDLIFE WILD

The nearby notices are very prominent but being ignored.  Some of the swans were eating out of the couple's hands and a loaf lay on the ground with one eating from it.  I did wonder if the swans knew them and thought initially that the man was examining them for their health but he would not have been giving them bread if that was so.  The geese quickly swam up to get their fill and a woman was feeding bread to a large flock of gulls on the other side of the river.