Nick Xenophon's threat to major parties in the upcoming South Australian election is undisputable and just over two months out from the poll his SA Best party has claimed their first ministerial scalp.

Former South Australian Liberal leader Martin Hamilton-Smith is quitting his position as Labor government Minister for Investment and Trade (among other portfolios) and has offered to campaign on behalf of Graham Davies, the SA Best candidate in his former seat of Waite. Before you suggest we sack our subeditor, yes, that is all factually correct: Hamilton-Smith has changed parties more times than an indecisive New Year's Eve reveler, and the number of challenges he's made to the various leaders he's served make our federal parties look positively loyal.