Plant is at my friend's place in the Sutherland Shire of NSW.
Don't think it is a Gymea Lily becaue of the multiple heads.. could be wrong. Any clues anyone?? Will it flower or is that it? & is it one that will die afterwards?
Agave species no doubt.
I agree; I think it may be Agave angustifolia, narrow leaved century plant.
Here is a link that might be useful: Agave angustifolia