On his fatherâ s side , Keynes is the grandson of Richard Keynes , the nephew of the Cambridge professor Simon Keynes , and the great-great-nephew of John Maynard Keynes , an economist . On his father 's side , Keynes is the grandson of physiologist Richard Keynes , the nephew of historian and Cambridge professor Simon Keynes , and the great-great-nephew of economist John Maynard Keynes .