Australian ABC website has an article "Costello backs Howard on Exclusive Brethren meeting"
its link is http://www.abc.net.au/news/stories/2007/08/22/2011667.htm
after some very brief research I came up with "Exclusive Brethren/Australian Federal Election, 2004"
which is at http://www.sourcewatch.org/index.php?title=Exclusive_Brethren/Australian_Federal_Election%2C_2004
For a group that do not vote and are considered by many to be "extremist" I'm not sure it's really appropriate for them to be having meetings with our Prime Minister especially if the agenda does not seem to have been made public.