eleven o'clock
The bird-catchers are after them about the middle of April , when they first come back to England . '' `` Do nightingales sing only at night , Tom ? '' `` No ; they sing pretty nearly all day long , only you do n't notice them because other birds are singing too . They begin their night song between ten and eleven o'clock , when other birds are quiet , and that 's the time to hear them if you happen to be awake . There 's Charley Foster 's house , that low white house on the left hand side of the road . There 's Charley , too , looking out for us . '' Charley was two or three years older than Tom , but having the same tastes they were often together .