Of course, the defeat of a throne speech is a confidence matter, and would have got us to the world we're in here, which is a debate about who a new ministry should be.
If you're inquiring into the political circumstances at the time, as opposed to the constitutional issues, I guess my answer is that the government had not made a terrible blunder yet that had united the opposition and created the political circumstances permitting such an act, which is my point that you have to make a difference between the constitutional rules and political realities.
Then the issue is about whether a constitutional or a legitimacy issue arises. I remember this being raised at the time. The throne speech had passed. I don't quite remember the details of where it was, but let's take it as read that it “passed”. Did that mean the government had survived a formal confidence vote and the matter could never again be raised, whether the House had confidence or not?
My answer is that you will not take that view when, perhaps years from now, you are back on the opposition benches. I think you will take the view that the House of Commons is always free to turn to the issue of confidence in a ministry, in principle, and can do so in many circumstances, the most obvious one being on defeat of a money bill, and also on defeat of a throne speech. I submit you could also hardwire into at least the Standing Orders some other specific ways, which everyone would know: this is a confidence vote that's properly before the House.
So that's my answer to your question. In terms of constitutional practice, it would be entirely appropriate, having given confidence in a government on Monday, to then vote it out on Tuesday. That's the genius of our system.