There has been considerable discussion with my Australian friends as to the identity of these birds. They were in bright sunlight and uniform in colour and there appears to be a hint of a white edge along the wing. The conclusion therefore is that they are Dusky Woodswallows.
Country: Australia
Location: Serendip, VIC
Family: Woodswallows (Artamidae)
Species: Dusky Woodswallow (Artamus cyanopterus)
Date taken: 21/11/2013