Mark Stuart: Backbenchers will soon end the PM’s honeymoon

The good news is that Cameron has a little more wriggle room than his paper majority of 12 might suggest. For a start, the four Sinn Fein MPs refuse to take their seats in the House of Commons. Add to that the likely support of the two Ulster Unionist Party MPs, and former UUP MP Lady Sylvia Hermon, as well as the fact that the Speaker and his three deputies tend not to vote, and Cameron’s working majority creeps into the low 20s.

One might think that the smaller the majority, the more it might encourage potentially rebellious MPs to toe the party line. Not so. Ask poor John Major. His slim overall majority of 30 in 1992 was soon whittled away by a combination of defeats in by-elections and a group of regicidal backbenchers campaigning against the Maastricht Treaty.

Momentarily, a small number of maverick MPs held the balance of power, touring the television studios dictating government policy. Whether it was Tony Marlow in his stripy blazer or Teresa Gorman berating the Common Fisheries Policy, John Major lost control. Indeed, Sir Norman Fowler, a leading minister under Major, even penned a memoir aptly entitled A Political Suicide.

Worse still for Cameron is the fact that MPs generally are becoming more and more rebellious. As new research by myself and Professor Philip Cowley at the University of Nottingham shows, the last Parliament from 2010 to 2015 was the most rebellious in the post-war period, with over one third of votes – 35 per cent to be exact – witnessing a rebellion by at least one MP. That trumped the 2005-2010 Parliament, which also broke the previous record, as did the 2001-2005 Parliament. More to the point, rebellion is like an addiction. Once you have developed the habit, it is difficult for MPs to stop. The problem in the last Parliament was that the vast majority of the 2010 intake of MPs who never held government jobs rebelled. So, one of the main jobs of Cameron’s new Chief Whip, Mark Harper, is to stop the 60-plus new MPs from the 2015 intake from developing the rebellious habit in the first place.

One thing that must improve is the running of the Conservative Whips’ Office. In the last Parliament, it was dysfunctional at best. The basic job of counting up potential rebels and then picking them off one-by-one simply wasn’t done, leading to the surprise defeat on military action in Syria in August 2013. Cameron’s new Whips’ Office needs to emulate Tony Blair’s formidable whipping operation.

But the fact that, unlike 2010, Cameron won the General Election outright will help party discipline in three respects. Firstly, the new MPs will, initially at least, owe a debt of loyalty to the Prime Minister, believing that it was his campaigning skills that got them elected.

Secondly, there will be more government jobs to go around, because there are no “pesky” Liberal Democrat MPs in the Government. Such patronage is the glue that keeps governments together.

Thirdly, Cameron can point to the Conservative manifesto as a banner around which all Tory MPs can unite in contrast to 2010 when there was only a Coalition Agreement which ordinary backbenchers disliked and had no say in formulating.

The problem, however, with the 2015 Conservative manifesto is that it contains lots of promises which the party leadership never thought in their wildest dreams that they would have to implement.

Almost no-one at Tory headquarters believed they would win an outright majority. Rather, the more inflated promises like the repeal of the Human Rights Act, were always intended to be negotiated away in coalition talks following a hung Parliament.

So, unexpected electoral success has left Cameron with an almighty headache. Faced with a likely rebellion led by Tory grandees like the former Chancellor Kenneth Clarke and the former Attorney General Dominic Grieve, egged on by the massed ranks of eminent lawyers in the House of Lords, the repeal of the Human Rights Act has been put into the long grass.

There is an old truism about British parliamentary politics that the most important relationship is not between Government and Opposition, but between a Government and its own backbenchers.

The real threat to party discipline in the current Conservative Government comes not from the Labour Party, which is in disarray, but from a group of about 60 right-wing Conservatives who will not be satisfied with anything less than complete withdrawal from the European Union.

Whenever the EU referendum is held, a very large number of Conservative MPs will feel compelled to abandon party loyalties in order to campaign on the “no” side. And at that point, Cameron’s dreams of maintaining party discipline will buckle and then break.

• Mark Stuart is a political biographer from York.