However much the Greens try and present themselves as a broadly based party of great social justice and concern, their electoral success or failure ends up getting back to trees.

It’s the images of beautiful forests being raped and pillaged by clear felling that stirs the anger in the hearts of suburban Australians who rarely see a real gum tree. Every time the Greens can engineer a confrontation about trees their vote goes up.

Which is why Bob Brown must be so very thankful to Tasmanian company Gunns. The misguided decision of the timber fellers to take environmental groups to court for defamation was help enough.

Every time the case comes to court it presents an opportunity for television stations to show clips of their handiwork as the trees come tumbling down. And now Gunns is pushing ahead with its plans for a pulp mill on the shores of the Tamar estuary.

Just as earlier plans to build a pulp mill on Tasmania’s north west coast turned an earlier generation of Tasmanians green, this proposal is galvanising another one.

The Greens are already a significant force in Australian politics and the campaign they will build around the pulp mill will guarantee they continue to be one.