Choc... Here's a link and a quote of the example I mentioned in my previous post (from the comments):
And yeah, you said premiership, but this is the same deal, essentially. As I said earlier, Queensland doesn't have a senate (they abolished it in 1922), but they still have the three month rule to get a seat, I think.
Antony Green said:COMMENT: The position of Prime Minister is not mentioned in the Constitution. As with all Ministers, the Prime Minister must be a member of parliament, though up to three months are allowed in which a Minister may not be in Parliament. The Constitution just says Parliament, it does not say either house.
John Gorton was a Senator when he first became Prime Minister following the death of Harold Holt. He resigned from the Senate and contested Holt's lower house seat, which he won and entered the House. So Gorton spent time as a Senator and as a non-member while he was Prime Minister.
The view is that Prime Ministers should only be Senators for short periods and the convention is they should be in the House. There is nothing to enforce that convention, but it would be very unwise of a government to try having a Senate PM for any extended period.
And yeah, you said premiership, but this is the same deal, essentially. As I said earlier, Queensland doesn't have a senate (they abolished it in 1922), but they still have the three month rule to get a seat, I think.