You're thinking of Hal Douglas.
Five Guys in a Limo: http://uk.youtube.com/watch?v=JQRtuxdfQHw
Don is the first one in the car and does most of the narrating.
Nick Tate - used to be a regular on SPACE 1999
and was recently in a 1st season episoide of "LOST"
(and IS Australian)
The voice on the phone that Don blows off, Hal Douglas was his main East Coast competition, sometimes referred to as the "East Coast Voice of God".
For comparison, here is Hal Douglas doing that infamous COMEDIAN promo: http://uk.youtube.com/watch?v=yXbFuNQwTbs
- Ed C.