a quarter to eleven
` When did they go ? ' ` It was about ten-thirty , sir , when one of the two gentlemen called me to bring my key and lock up the vault . The vault was properly locked , first with his key , and then with mine , and then he left . Perhaps it might be a quarter to eleven , sir . ' ` But the other gentleman ? ' ` Oh , he must have slipped off earlier , sir . I did n't see him go . '