John Farnham makes a guest appearance in the 1975 Crawford Productions sitcom The Last of The Australians, starring Alwyn Kurts and Rosie Sturgess. John plays a very keen vacuum cleaner salesman in an episode titled 'Ashes to Ashes', which also features actor Terence Donovan.
Although just a brief scene, John doesn't miss a beat and is straight into character. He appropriately hams it up with the other cast members, which is in keeping with the tenor of the scene.
For someone who, until the mid-1970s, was more renowned as a pop singer, this clip is a good example of some impressive acting chops.