Mourning finished 10th in the "Consolation Race" for over 1500cc. cars and Formula III cars.  That explains the small open-wheeler chasing him.  If the blurry number on the little car is #212, then it's Stuart Dane in his Dane-Triumph Special.  He DNF'd with a "lifted barrel".  (Those of us who've owned British twins have heard of, if not suffered, that problem.)