A drilling system including a drill head. The drill head defines a drill head bore and includes a drill head bore closure device. An inner core barrel and an inner core barrel retrieval device may be passed through the interior of the drill string and the drill head bore when the drill head is connected with the drill string and the drill head bore closure device is actuated to an open position. A method of wireline core drilling which includes passing an inner core barrel retrieval device through the drill head bore and into the interior of the drill string when the drill head is connected with the drill string, and removing an inner core barrel and the inner core barrel retrieval device from the interior of the drill string through the drill head bore when the drill head is connected with the drill string.