Midnight Gardeners

Someone has planted four saplings out the back. They sit on the little hillock which looks out on the playing fields; When they are grown, they'll block the view of the houses over the way, but we'll still see the regular insanity of football practice, cricket practice, rounders practice, dog exercising, metal detection and golf that keeps the local community entertained.

Last night I went to bed, no trees. This morning I got up, trees. Who is planting them and why do they do it in the middle of the night?