Iain Martin marvels at Cameron’s decision to recall the House of Commons for today’s vote:

It remains baffling. Why on earth did the Conservative leader and his aides not war-game this properly? Their strategy was predicated on the Labour leadership falling in to line behind intervention [bold mine-DL]. It was always a daft presumption, after Iraq and with public opinion so sceptical of more involvement in foreign wars. And Cameron’s team overlooked or ignored that many Tory MPs were equally sceptical.

If I had to guess, I would say that Cameron and his aides must have assumed that the opposition would submit to whatever the government wanted just as every Tory leader did when Blair was Prime Minister. It may never have occurred to them that Miliband would take advantage of the extraordinary unpopularity of going to war in Syria to embarrass the government, because that is the sort of thing that they never did and would never do while in opposition (and that’s definitely not a compliment). Because of that, they dismissed dissension in the government ranks as irrelevant, and they expected that the public’s opposition to another war would never enter into it. Cameron gambled on the assumption that enough Members of Parliament would have as little respect for public opinion as he does, and it backfired on him in what Fraser Nelson has called “one of the most spectacular parliamentary defeats in modern political history.”

Nelson continued:

It looked like an Iraqi Groundhog Day – and all for what? So Britain could piggyback on an American military strike on Syria, to help an America that doesn’t need our help anyway?

That is what makes Cameron’s gamble harder to explain. He originally positioned himself as a Tory leader that wanted to be less reflexively supportive of whatever the U.S. wanted to do overseas, but since he has been in office that isn’t the way that he has governed at all. It is fitting that he should suffer one of his biggest political setbacks as a result.