Just spotted the following at the John Novello's website:
Don Leslie, the inventor of the Leslie Rotating Speaker recently departed this world. My hats off to this incredible inventor because the marriage of his speaker invention to Laurens Hammond's organ created the Hammond Organ/Leslie Speaker combination that literally rocked the music world from 1935.
Not only the Hammond, but also favoured by the more progressive folk guitarists. The best example of whom, I can think of is John Martyn, and well displayed in action on Martyn's Live At Leeds Cd (with free jazz drummer John Stevens, and the English folk scene's favourite double bass player Danny Thompson).