The pilot had flown the aircraft to Hungerford to attend a Field Day. The following morning he adjusted the aircraft brakes and apparently decided to take the aircraft for a test flight. After taking off from the local racecourse, the aircraft climbed to about 150 feet above the ground before descending to fly just above the tops of the trees. The flight continued at this altitude until the aircraft struck a single wire power line and spun to the ground. The pilot had discussed the presence of the wire with the owner of the aircraft prior to taking off. However, the wire was of small gauge and not easily discernible from the air.