St. James's Park: Karate Kid
More unexpected in large.
There was a feeding frenzy on, and the greylags kept surprising the little cow geese into flappy fits. This littlest Ross's goose surprised the nearby greylag with its (over-)reaction.
My best pictures were actually of a posing pigeon, a hand-shaking squirrel, and a poker-faced greylag, in spite of the more exotic action (inc. the pelicans flying, feeding, and facing off against a heron).
Other drizzly St. James's Park pics on Flickr here (or right from the posing pigeon).