In 1974, Laithwaite was invited by the Royal Institution to give a talk on a subject of his own choosing. He decided to lecture about gyroscopes, a subject in which he had only recently become interested. His interest had been aroused by an amateur inventor named A Jones, who contacted Laithwaite about a reactionless propulsion drive he (Jones) had invented. After seeing a demonstration of Jones's small prototype (a small wagon with a swinging pendulum which advanced intermittently along a table top), Laithwaite became convinced that "he had seen something impossible". In his lecture before the Royal Institution he claimed that gyroscopes weigh less when spinning and, to demonstrate this, he showed that he could lift a spinning gyroscope mounted on the end of a rod easily with one hand but could not do so when the gyroscope was not spinning. At this time, Laithwaite suggested that Newton's laws of motion could not account for the behaviour of gyroscopes and that they could be used as a means of reactionless propulsion. The members of the Royal Institution rejected his ideas and his lecture was not published