I posed this question to my frendly local FOI the simple answer was yes you need to keep a record of flight and duty for private operations if your a flying comercial pilot. His Interpretation of the regs sure but Interpretations be dammed cao 48 is there to protect us from overwork and fatigue related accidents why not follow it ? also the coroners court would not be so interested in wether the people sitting behind you were paying or not during the flight hours previous to an incident / accident.