Now we're back in Mrs. Shears' yard, and the police have just arrived. Christopher likes the police, because they "have uniforms and numbers and you know what they are meant to be doing" (11.1).
In other words, their consistency and order make him feel safe. (Read more about order and safety in our "Themes" section.)
One policeman leads Mrs. Shears into her house and the other one walks over to talk to Christopher. (Remember, he's still crouched on the ground, with his face in the grass.)
They don't have such an easy time talking.
First, Christopher answers the policeman's questions very literally, and the cop is confused. (For example, he asks what Christopher was doing in the garden. Christopher answers honestly that he was holding the dog, but the policeman just wanted to know why he was in the garden in the first place.)
Then the policeman starts asking questions very quickly (like "Did you kill the dog?" and "Is this your fork?") and Christopher gets a little freaked out and overwhelmed (11.17, 11.19). We would be, too. Not cool, Mr. Policeman.
To make himself feel better, Christopher lies back down on the grass and starts groaning, which he finds very calming. (He compares the groaning to white noise.)
The policeman tries to pick Christopher up off the ground. Christopher doesn't like this one bit, and so… he hits him.