If you speak to BA they will tell you any travel involving Australia counts as 4 continents. AA are not wrong. The rule is a pain.
As Darren says you do not have to go round the world with the oneworld Explorer. I was in the BA Shop in Edinburgh on Saturday and the agent explained we could return from Oz via JNB if Africa took your fancy.
[This message has been edited by Gaza (edited 09-20-2001).]