Removing the sign wouldn't have been easy, as it was professionally installed.

"It was secured to the fence with a big heavy frame so it couldn't have been kids", Cowan said.

He suspects it was Labor supporters.

"I was thinking it must be Labor or Liberals, but the Liberals, why would they care? They have no chance [of winning Wills]. And we have seen a lot of defaced posters with nasty words and teeth blackened out in Wills."

Cowan searched the streets around his home and the local park but couldn't find any trace of the sign.

"It would have taken a few strong people and probably an axe to take it off, and they must have put it into a car pretty quick," he said.

In the neighbouring seat of Batman, the Greens have also accused Labor of dirty campaign tactics, including graffitiing sexist slurs on candidate Alex Bhathal’s campaign HQ.