What was the Sydney harbor Brudge scandal in 1932?

On the day of the official opening (Saturday 19 March 1932) the NSW Premier the Honourable John T Lang declared the bridge open, but was upstaged by Captain Francis De Groot of the New Guard who rode up and slashed the ribbon with his sword before Lang cut it. The New Guard was opposed to Lang's leftist policies. De Groot's organisation resented the fact that the King's representative in Australia, the Governor-General Sir Isaac Isaacs, hadn't been asked to open the bridge. De Groot was arrested, and the ribbon retied, allowing Lang to complete the official opening ceremony.