Since 1979, there have been only two general elections where the winner has been uncertain: 1992 and 2010. In every other contest it’s been possible to name the victor several months, if not years, in advance. And even in 2010 it was possible to say with certainty what wasn’t going to happen (the return of a majority Labour government).

For there not to be a ‘game over’ moment in advance of a British general election in recent history is very much the exception. It is not merely the benefit of hindsight to state that it was clear the Tories were going to win in 1979, 1983 and 1987, or that Labour would triumph in 1997, 2001 and 2005. In each case there seemed to be internalised within the political class and the media a belief, almost an acceptance, about the outcome.

This was true of party leaders as well. Both Jim Callaghan in 1979 and John Major in 1997 privately conceded defeat months before polling day. Read political diarists from across the spectrum and you’ll find references to the “inevitability” of Tory wins in the 1980s and of Labour victories in the late 1990s/early 2000s.

The recent strengthening of Labour’s lead in the opinion polls led me to wonder whether we’ll get a “game over” moment this time around. Might there come a point where the fact that Labour has been ahead of the Conservatives in the polls for such a long period of time* starts to make people think, make them really think, that Ed Miliband is going to be the next prime minister?

I ask this question as much of myself as anyone else. I look at the poll averages and contemplate how they would, if repeated on polling day, produce a Labour government… yet at the same time I predict a hung parliament with the Tories only four seats behind Labour.

What is missing from the current context that was present during the Thatcher and Blair years, which made their election victories so predictable?

One answer is within the question itself, and that is we’re missing a Thatcher or a Blair. At the moment we don’t have any party leaders with personalities that shape their parties – at least, not in the eyes of the media or the public.

Thinking back to those elections where the result wasn’t a foregone conclusion, you could say that neither John Major in 1992 nor David Cameron in 2010 were able to command quite enough personal momentum to render their journey to Downing Street feel inevitable.

Both won power against different sets of odds and expectations. This was mirrored in opinion polls that implied either the opposite eventuality (1992) or an uncertain outcome (2010).

Other factors worked in Thatcher and Blair’s favour: a divided or weakened opposition; an existing majority that was so large as to make defeat almost impossible (particularly true in 1987 and 2001); and a sympathetic media.

None of these are present for either David Cameron or Ed Miliband. And this time round there is an additional factor to compound the uncertainty: Ukip.

I remain convinced that Ukip will not win a single seat next year, but it’s the impact the party may have on the results in some marginals, particularly Labour’s top targets, that is one of the great unknowns.

Nigel Farage is somebody whose personality wants to shape his party, but ends up doing so in an oblique way. Ukip is both a part of and apart from Farage. Candidates rely on him for promoting and popularising the Ukip brand, but the brand is one that appears to encourage if not flourish upon a range of viewpoints that are not always compatible or consistent. As a consequence, Ukip may shape some of the contours of next year’s election campaign, but not to its own benefit.

I know I’m not alone in hesitating to “call” the election for Labour, or for any other party for that matter. There are a few voices declaring the opposite, however, and who have stated that Labour has already lost the election.

Dan Hodges is one of them, and has been saying as much in the Daily Telegraph for a number of months. For him, there has already been a “game over” moment – and it’s game over for Ed Miliband. John Rentoul of the Independent shares this view, and has been forecasting it from almost the day Miliband became Labour leader.

By contrast, George Eaton in the New Statesman began 2014 by predicting Labour would finish the year five points ahead of the Tories in the polls. But he went on to add that speculation will “increasingly focus on whether Labour will win an overall majority or, alternatively, become the single largest party, with many Tory MPs resigning themselves to defeat.”

All three of these writers have one thing in common: none of them are precisely sure which party or parties will win. I suspect this position could prevail right up to polling day. In 2010 it was pretty clear by the end of the campaign that the Tories would end up the largest party. In 2015 even that kind of prediction might not be easy to make.

Even though the mathematics of the polls suggests one thing, instinct will continue to suggest another – at least until one of the party leaders starts to both feel and act like a prime minister in waiting.

*Since early 2011 in fact, barring a couple of weeks at the start of 2012.

Update: Thanks to Stefan Stern, who tweeted me to say that both he and Mehdi Hasan have for a number of years predicted that Labour will end up the largest party at the election. Here’s Stefan’s most recent article.