They should have seen it coming. A government defeat on an issue of war may be unprecedented, but defeat on the Syria vote did not come out of the blue. You can certainly blame poor party management, failure to prepare the ground, underestimating the poisonous legacy of Iraq — but such failings are common enough. The biggest single factor is one that ministers, the media and MPs themselves have failed to understand: Parliament has changed.

The consensus has long been that Parliament no longer matters. It is assumed to be the docile creature of the government, full of spineless or ambitious MPs who are the slaves of the party whips. In fact, unnoticed and under our noses, that has been becoming progressively less and less true throughout my 30 years in Parliament. The parliamentary kraken, slumbering in the deep, has been gradually awakening. Each successive Parliament since the early 1970s has been harder for the whips to control. The scale and frequency of backbench revolts has inexorably increased.

Ted Heath faced rebellions over the Common Market but from today’s perspective those were minor, and soon surpassed by revolts against Harold Wilson, who tried to subdue his backbenchers by threatening to withdraw their party membership, which he contemptuously likened to a ‘dog licence’. Mrs Thatcher suffered some 4,259 votes cast against her during her 12 years in office. Tony Blair’s determination to maintain iron discipline prompted the joke: ‘What is the difference between a New Labour MP and a shopping trolley? A shopping trolley has a mind of its own.’ But the rise in rebelliousness continued unchecked. In Blair’s 12 years he had to put up with no fewer than 6,520 votes against him by his own MPs; indeed, he suffered the largest rebellions since the Corn Laws.

It should be no surprise that this Parliament has been the most rebellious ever. But this trend, though meticulously recorded by Nottingham University’s Philip Cowley, has been largely ignored. Commentators preferred to sneer at contemporary MPs and believe in a golden age when independent-minded knights of the shire, free from ambition, supposedly held governments to account. That is a myth. Parliament in the 1950s was a docile lamb. Whole sessions would pass without a single MP voting against their whip. Now rarely a week goes by without some -dissent.

Because this change has been ignored, little effort has been made to explain it. My own experience over three decades in Parliament suggests it is the result of several mutually reinforcing developments. First is the growing interaction between MPs and their constituents, which has been much amplified by the advent of the internet. When I was elected in 1983, if a constituent had written asking me to vote against clause 12 of the Widgets Bill, I would probably have sent them the standard Conservative Research Department reply. I would hear no more. In subsequent parliaments, not only did the volume of correspondence rise exponentially but electors started to rebut the official reply. I would be forced to draft my own more convincing defence. Since the spread of the internet, constituents are more likely to reply criticising even my persuasive prose. Forced to look into a question from first principles, I am sometimes compelled to admit that the critics are right.

At the same time, the voters themselves have become less tribally loyal to political parties. MPs sense that an increasing proportion of their voters are choosing on personal assessment of the candidates, single issues or local questions rather than party loyalty. And websites such as theyworkforyou.com make it easier than ever to see how an MP voted on gay marriage, war or Europe.

That brings us to the third change. A whip’s most powerful appeal is to MPs’ ambition. After my first rebellion, one said to me: ‘What a shame — you had such a promising career.’ I was chilled, although the threat was for some reason not implemented. But now an MP’s fear of losing his seat may well trump the threat of losing out on a promotion which would be impossible without it.

As a result, Parliament is becoming more like it was in the 19th century. Governments, rather than relying on threats, must convince their backbenchers of the case for each of their measures, do deals with other parties or make compromises over their legislation. On the whole, that is a thoroughly good thing. I find Parliament even more worthwhile now than when I was first elected.

There is a downside, of course. If MPs swing with every short-term breeze of opinion, governments will be unable to pursue measures which are unpopular in the short term even though beneficial in the long term. But that is not inevitable. In my experience, voters respect MPs who are prepared to back unpopular policies if they are forthright in defending them and do so from conviction rather than coercion. I was warned that my advocacy of legalising cannabis would be electorally damaging. However, the readiness with which people now enter into dialogue with their MPs meant that I could respond to objectors. I probably persuaded few, but they invariably expressed respect.

Above all, governments (and commentators) should accept that Parliament has changed. They must accept that rebellions and even defeats will happen but are not the end of the world, nor the end of the government. The true lesson of the Syrian vote is that Parliament is back.