As one supporter at a Corbyn rally put it: "When I go out canvassing, people don’t say “you’re too left wing in the Labour Party”, they say “you’re all the same as each other!”’

Few would argue that “you’re all the same” is not a common trope about politics. But the extension of the idea - that Labour remains out of power because it is not left wing enough – remains controversial and has been the cause of some of the bitterest debates in the current leadership contest.

Differentiation vs demand

From a marketing perspective, it would appear that both sides have a point. If you want to bring a new product to market, your investors will want to know both if there is demand for it and how it is different from what it is already available. The ideal is to have a product that meets both these criteria, but in mature markets (of which politics is among the oldest), some trade-off may be necessary. This is because the most in-demand features of that particular market already tend to be set (for example, strong leadership or competence running the economy) and are already dominated by the market leader. You therefore either have to wrestle trust on these important features off the current market leader or try and make a new feature the most important factor in your customers’ decision making process by offering something different (but risks being rejected as they are more untested).

Much of the debate within Labour revolves around where the correct pivot point is in this trade-off between offering what the market already wants and something that’s different.

As Phil Collins has pointed out, emphasising the importance of differentiation goes back to the battles of Bevan and Gaitskell. As the former thundered: “What is the common factor that Labour people share and which sharply distinguishes us from the Tories? It is Socialism . . . The more we play it down…the less reason there is for people to vote for us.”

Differentiation and GE2015

The big issue for those that share Bevan's diagnosis is that when it comes to the last election, the public was well-aware of the differences on offer - and chose to reject Labour.

The chart below shows that prior to the election, the vast majority of voters thought that Labour and the Conservatives were different in their visions for the future of the country, their attitude to the economy and their attitude towards government spending. Contrary to what some might say, the public did not think that the choice on offer was just different shades of austerity. Labour did not lose because they didn't offer a big enough alternative to the Conservatives on the big issues.

If anything, this graph shows some of the reasons why the Tories won: the NHS was meant to be Labour’s core area of strength, but fewer voters thought the two parties were different in this area than in others.

Indeed, the key to marketing strategy is to be similar to your competitors on their areas of strength and different to them on your own areas of strength. Lower-end brands emphasise their similarities to their better-known counterparts in terms of quality while simultaneously highlighting their differences when it comes to price. Better-known brands try to turn this on its head, using the existence of replicas to draw attention to differences in quality (being “the real McCoy” or “Just like a Golf”).

The story of the 2015 election can, in part, be told by the way the Conservatives reduced the difference to Labour on the NHS while maximising the difference between the parties on the economy.



Corbynmania

Of course the big exception to all this in the graph above is “the background that their leaders are from”. This was the only feature of the two main parties where more voters thought they were similar than different.

And perhaps here lies the difference between Jeremy Corbyn and his rivals for the Labour leadership. Set against three candidates seen by some as typecast, identikit and “careerist”, he appears genuinely different and authentic. With a skilled campaign manager in Simon Fletcher holding fort, the battle quickly became “Corbyn vs the others”, in turn making them look relatively interchangeable. The ever-increasing howls of warning from the party’s past have seemed to highlight Corbyn’s mild-mannered reasonableness (as the only candidate personally not to go negative) and sense that he is a break from the party’s recent history.

Labour’s centrists are right to say that Labour’s loss should not be diagnosed as a result of not being ideologically left-wing enough. But perhaps the non-Corbyn characters have been held back by being seen as just the same as what’s previously been on offer. Blair’s youth and warmth once contrasted with a grey and tired Conservative government. But now all leaders seem to be brown-haired, early middle-aged, ex-special adviser, on-message politicians, some parts of the electorate yearn for something else. Alan Johnson and Dan Jarvis, with their extraordinary personal stories remain alluring, but neither could be persuaded to stand this time around.

Our polling on the race this weekend suggested that David Miliband was more appealing to the public than any of the current candidates, which could suggest that the archetype politician image can be effective if combined with gravitas. Alternatively, he provides a hint of "wanting what you can't have" - perhaps the same thing driving support for Corbyn among Labour’s left wing which has felt suppressed for nearly three decades and fed up of being told they can't have an uncompromisingly left-wing leader.

Whatever the result on 12 September, Labour is in dire need of someone personally different enough to the current status quo, but with an ideological offer broad enough to appeal to a diverse and increasingly fragmented electorate. The alternative to this is either being an own brand Hovis knock-off or a niche Rye bread baker serving a small market loyally. Neither are likely to have enough appeal to secure the 11 million voters necessary to win a parliamentary majority.

Adam Ludlow is a senior consultant at ComRes.