twelve o'clock
`` Well , perhaps she would . You 've got a head on your shoulders , Cynthia -- that you have ! Miss Meldreth would have to get to Mrs. Vane and tell her this morning , as she said ; then Mrs. Vane would let the police know . That gives us till about eleven or twelve o'clock . '' `` Two hours ' start . Is not that sufficient ? '' Westwood shook his head .