There are seven basic plots in politics.

Just as in Christopher Booker’s analysis of literature and film, I believe there are seven basic stories being played out in the careers of almost all significant politicians, which repeat themselves endlessly, and have done for centuries:

1. Principled or maverick individual succeeds because of their principled or maverick approach; power changes them, leaving their supporters disappointed.

2. Charismatic would-be king is thwarted by ruthless, unworthy opponents; and ends up exiled and frustrated in life.

3. For years, the heir to the throne yearns restlessly for the crown; finally gets it – at some price; but fortune turns against them.

4. Two individuals rise to power together; but eventually destroy one another, either through blind loyalty or the emergence of distrust.

5. A great individual has one fatal flaw or makes one great mistake which undoes them and damages their reputation.

6. A ruthless leader lives and dies by the sword, destroyed by their own pride and paranoia, and often assassinated by their own protégés.

7. A canny foot-soldier rises to the top, using the mind more than the sword, but is never comfortable with power and is replaced by a more natural born leader.

There are three other plots which exist purely in political fiction:

1. The thwarted and exiled would-be king comes back a wiser, stronger person, takes the crown, and rules successfully.

2. A young rogue with bad habits or fatal flaws corrects their habits and flaws, becomes a changed person, and rules successfully.

3. The principled or maverick individual retains their principled or maverick approach even when they obtain power, and rules successfully.

Of course, all these plots – other than the fictional ones – end in failure, and those politicians who manage to navigate a successful end to their careers are so rare that they don’t warrant a ‘plot’ of their own.

But it’s a useful exercise for politicians to look at that list of standard plots, work out which film they’re in and what fate they’re headed for, and try to change the script. For that reason, I believe every politician should be a film and literature buff – able to recognise a narrative arc when they see one, and have a clear sense of how the story will play out.

That brings me to the film that David Cameron and his entourage watched on the eve of the Conservative party conference a year ago today.

Hamburger Hill.

Whether it was the watching of the film that inspired the naming of the strategy, or the naming of the strategy that inspired the watching of the film, we know – from Allegra Stratton’s fine column written a couple of weeks later – that senior Tories now refer to their economic and deficit strategy as ‘Hamburger Hill’.

For those who have not seen the film, it’s a realistic if formulaic depiction of one squad’s experience during the American assault on Hill 937 near the Laos border in May 1969, and it’s easy to see why it inspired David Cameron.

From his point of view, the parallels are obvious. The hill is a hugely-challenging target with an entrenched enemy, against which the Americans launch a relentless, full-frontal assault. In the film, the squad – despite heavy casualties – retain their morale and camaraderie, and stick to their mission; they rail against the lily-livered critics back home and the media doubting their ability to get the job done; and at the end of the film, exhausted but triumphant, they bask in their hard-won victory.

The trouble is if the Tories look beyond the fictionalised account, they’d have learned that the real Hill 937 battle is viewed as a tactically inept, strategically pointless disaster, encapsulated in the fact that – unmentioned in the film – the Americans surrendered the hill just days after finally capturing it. The unacceptably high casualties from the battle succeeded in turning American public opinion even more firmly against the war, and led the White House to order an end to similar operations. Not exactly the model for economic policy it seems.

Of course, there is an interesting parallel between Vietnam and the current debate about the Government’s economic and deficit strategy.

Just as in Vietnam, many individuals within government and the media are telling themselves that if the Osborne strategy doesn’t seem to be working in terms of delivering economic growth or bringing the deficit down, it’s not that the strategy is the wrong one, it’s just not being implemented fast enough or on a big enough scale. Thus in Vietnam, successive American administrations carried themselves deeper and deeper into the quagmire, at unimaginable cost to their own forces, to American society, and – most of all – to the people of Vietnam, Laos and Cambodia.

If David Cameron is indeed taken by Vietnam films, he could do worse on the eve of his conference next weekend than watch The Fog of War, the brilliant series of interviews with former US Defence Secretary Robert Macnamara charting the descent into the Vietnam quagmire, and hearing his regrets about all the missed opportunities to change course. Unlike Hamburger Hill, that film has the virtue of being the truth.

Incidentally, watching Ed Balls’ speech earlier, I was reminded by his ‘Butch Cameron’ line of an important movie parallel in terms of Labour’s economic strategy.

Two years ago, almost every senior voice in the Labour party – with the exception of the trade union bosses – was telling the party they had two choices: they could either back the Tory economic and deficit strategy 100% in an attempt to neutralise the issue; or they could back the speed of the proposed deficit reduction plan, but disagree with some of the specifics about where the cuts and tax rises should fall.

With either option, Labour would have been damned in 2015. If they backed the pace of deficit reduction and the Osborne plan succeeded, then the Coalition would be able to claim they’d achieved their mission and deserved another term in office, regardless of any disputes about how the deficit had been reduced. But if Labour backed the plan and it failed, the public would tar all parties with the blame, again regardless of any nuances over where the cuts had fallen.

Ed Balls introduced the third choice: opposing the pace of deficit reduction and saying the whole strategy would prove counter-productive. If he was wrong, Labour were damned anyway. If he was right, then they’d have the chance of a hearing with the public. He did the only thing that gave Labour a chance.

It reminded me of the scene in Butch Cassidy and the Sundance Kid where the posse has the pair trapped on the edge of a ravine. Their only choices are to ‘give’ and go to prison, or ‘fight’ in which case they’d be killed or starved out.

Butch Cassidy introduces the third choice – jumping off the ravine – the most dangerous of all the options but the only one that gives them a chance.

Obviously there was a bit more economic theory at work when Balls defined Labour’s position on the deficit, but I’d like to think there was a bit of the film buff at work as well. Either way, as long as he and Ed Miliband avoid both Bolivia and Plot 4 in my list, they might just succeed.