Originally Posted by Chris

That would be constitutionally difficult. The PM doesn’t have the power directly to prorogue Parliament. The Queen does. He would have to ask her to do it, and would be doing so explicitly to prevent Parliament exercising its sovereign right to make legislation. Setting the Crown and Parliament against each other in that way would be constitutional dynamite. If it were known that a PM was considering such a move, I predict a message would arrive from the palace saying something along the lines of, “if you were minded to ask for a prorogation, her majesty would be minded to refuse.” As a result of which, the constitutional integrity of the United Kingdom would be preserved by the PM not asking, and Her Maj not having to refuse, and Parliament carrying on as it sees fit.