At this autumn’s party conferences, the battle lines are being drawn for an election campaign that will be nasty, brutish and long. And extremely difficult to predict. Anyone who claims to be sure of the outcome is either a liar or a fool. I met a few of both at the Labour and Tory conferences, but on the whole, strategists of the different parties agree on this: None of them would bet a lot of their own money on the outcome.

Most of Britain’s elections since 1945 have not really been contests; they have been coronations. The winning side is usually obvious long beforehand. You did not have to be paying much attention to see that Tony Blair was going to win in 1997 or that Margaret Thatcher would prevail in 1987. When they look ahead to May 2015, there is no one who thinks a landslide parliamentary majority is on the cards. For most of Britain’s post-war history, the winning party took office with a vote share of 40 per cent or better. Neither Labour nor the Tories looks capable of achieving that. The highest ambition of both sides is to just get over the line. If I could today guarantee to either David Cameron or Ed Miliband that they would get a majority in single figures they would snatch my hand off.

This limited ambition is reflected in the way they are preparing for the fight. The Tories have what is called a 40/40 strategy. Its aim is to hold their 40 most vulnerable seats and take 40 from their rivals. By picking off a Labour MP here and a Lib Dem there, they hope to just about muster a parliamentary majority, but it would hardly be one to boast about. Many Tories privately concede that their most realistic ambition is to emerge as the largest party in another hung parliament. Labour vehemently denies that it is hoping to stagger into office with the support of barely more than a third of the voters: The “35 per cent strategy”. Yet, the evidence from their Manchester conference suggests that is exactly how they hope to put Miliband in Downing Street.

There are many reasons why neither party is aiming higher. The old blue-red duopoly over British politics has been in decades-long decline. From its peak in 1951, when Clement Attlee and Winston Churchill won more than 96 per cent of the vote between them, it has been steadily downhill. The meta-fact of contemporary British politics is that around a third of voters now reject both the blue tribe and the red clan. It is proving beyond either Cameron or Miliband to find a way of giving their parties an appeal that can command high degrees of support spread widely across the country. Both would like to think of themselves as “One Nation” leaders. Neither can truly claim to be so. The Tories remain chronically weak in the areas of the Midlands and northern England where they would need to win seats to achieve a decent majority. Labour, which only has 10 non-London MPs below a line drawn from the Wash to the Severn, continues to struggle in southern England. Labour is not even competitive in the Clacton byelection, a seat it used to hold.

The growth of multi-party politics combined with an electoral system designed for only two runners is another reason why this election will be both fierce and hard to call. Ukip is now polling in the mid-teens and Douglas Carswell will win Clacton to deliver the party’s first MP elected wearing its plum custard colours. One Tory strategist predicts: “Carswell will walk it.” Even if the Ukip vote is squeezed down at the election, as the Tories believe it can be by polarising the choice as one between them and Labour, it is now universally assumed that Nigel Farage’s gang will do much better than the 3 per cent they scored at the last election. The general assumption among Labour people is that Ukip will continue to deal most hurt to the Tories by splitting the vote on the right, but a recent Fabian Society study warns Labour that it may not be so simple as that. In some places, a strong showing by Ukip could split the Tory vote to the benefit of Labour or the Lib Dems. In other places, it may be that Labour pays a price as angry, less affluent voters defect to the Farageistes.

I sense increasing anxiety in Labour’s ranks about Scotland where the weakness of the party north of the border was exposed during the referendum campaign. It is a good bet that Labour will shed seats to the Nationalists. Though defeated on independence, the Scottish National Party will tell Scots that they need to maximise the number of Nationalists at Westminster in order to ensure that the UK-wide parties deliver on their promises of more devolution. The majority for independence in Glasgow, once an impregnable red fortress, is sending shivers up Labour spines. Labour is also worrying that some of its potential vote is leaking away to the Greens who have been quietly nudging up in the polls.

Then there is the Lib Dem paradox. Their most endangered seats are those where the challenger is Labour. Labour is likely to make gains at the expense of Lib Dems in northern England, the Midlands and London. The Tories are also hoping to pick off some Lib Dems seats, especially in the Eurosceptical west country. Yet, in Tory/Labour marginals, Tories will be hoping that the Lib Dem vote is resilient and does not break in a big way to Labour.

The Lib Dems are relying on the power of incumbency to save many of their MPs. They may be right that it will. Sitting MPs appear to have become harder to dislodge. I know that is difficult to believe. At a time when Westminster is so despised, can it really be true that it is an advantage to be a sitting MP? It may be counter-intuitive, but it appears to be true. At the last election, when voter anger with the expenses scandal was hot, incumbents broadly secured higher votes relative to new candidates. This may be partly down to local name recognition and organisation. It may also have something to do with hard cash. The taxpayer support for an MP — which is not, of course, available to a challenger — is now considerable. One senior Tory figure estimates it to be worth £1 million (Dh5.86 million) per MP over a parliament.

So the stage is set for a struggle that will be furnace-hot and at the same time narrowly fought in a highly concentrated number of battlefields. Whoever ultimately prevails, this fight for power seems destined not to produce a triumphant winner so much as a least-worst loser.

— Guardian News & Media Ltd