The pilot forgot to select the landing gear down before landing and the aircraft touched down with its gear retracted. The pilot reported that he was under a number of pressures which may have contributed to his forgetfulness. His sleep the night before the accident was disturbed and he had accumulated a delay in his tasking during the progress of several flights prior to the accident landing. One of the passengers on the accident flight was a high profile local identity. His presence may have influenced the pilot's decision to continue the approach to landing after finding that the approach was faster and higher than normal. The landing gear warning horn did not sound because the warning horn circuit breaker had been pulled by the pilot. The pilot had developed this habit whilst flying in another aircraft where the warning system was operating incorrectly.