Yes, and the PM took full responsibility for the action. There’s no doubt it was a political call on his point, but that’s what the PM is supposed to do. His estimation was that the so-called coalition was too fragile to warrant dissolving Parliament and would fall apart on its own.
That’s exactly what happened. The prorogation was over the Christmas period, and by the time Parliament re-convened in January, the Liberals and the NDP had taken a shellacking in English-speaking Canada, over getting in bed with the sovereigntist Bloc quebecois.
If he’d tried to avoid Parliament for several months, Her Excellency might have reached a different conclusion, but six weeks over Christmas? Didn’t seem that big a deal, and the PM took full responsibility for his advice to her.
The Queen wouldn’t be involved. The GovGen is given full authority by the Letters Patent to exercise all the powers of the Queen, except the few things that are reserved for Her Majesty (namely, appointing the Gov Gen and appointing extra senators).
There was a recent example at the provincial level where the Lt Gov of BC had to exercise the reserve powers. The BC election of 2017 returned a hung parliament. The Liberals had the greatest number of seats, but not a majority. The second party, the NDP, reached a deal with the third party, the Greens. The NDP/Greens had a majority of one, but if they elected the Speaker, the House would be equally divided.
The Liberal Premier advised the Lt Gov to call a new election, arguing that the current house was unworkable. The Lt Gov refused that advice, saying that it was up to the House, and only if it proved unworkable should there be an election. The Liberal premier resigned, and the Lt Gov called on the leader of the NDP to form a government. A year on, it seems to be working, confirming the Lt Gov’s instincts to let the political process play itself out in the House.