In Harry Potter and the Philosopher's Stone, the Mirror of Erised shows everyone what it is they most desire. Margaret Beckett's 35-page report into Labour's surprise defeat in 2015 serves a similar function: every bit of the Labour party will have something it can cling to.

Supporters of Jeremy Corbyn will take heart from the fact that individual left-wing policies, like the mansion tax, were popular. But Corbyn-sceptics will note that it was voters that went for Tony Blair and David Cameron that failed to back the party in 2015, which they will take as an endorsement of a centrist approach. Ed Miliband's diehard supporters - they do exist, believe it or not - will see the report as an endorsement of the Miliband era policy approach but will argue that a more convincing frontman would have sealed the deal.

Nor does the report offer a particularly useful way forward for Labour. A failure to win trust on "issues of connection" ie. welfare and immigration is blamed in part for the defeat - but whether that involves a harsher tone or "winning the argument" for either high immigration, higher social security or both is left unclear. Labour divides into four quarters on this: those who believe that the party must be unapologetically for both, those who believe that tighter controls on immigration will allow a more generous welfare state, those who believe the reverse, and those who believe that a rethink is required on both policy areas. None of these groups can say with any honesty that the Beckett Report provides them with any clarity as to which approach to pursue.

As for the question of whether to "defend the record", that, too, remains uncertain. This is as much a divide of attitude as left versus right. Ed Miliband, who led Labour from the soft left, believed that he could turn the page on New Labour and therefore escape the consequences of the 2007 financial crisis, a view he shared with Blairites who believed a "clean skin" from the 2010 intake, such as Chuka Umunna, was needed to win in 2020. But, equally, that Miliband doomed himself by not defending the record sufficiently is one shared by Labour figures as diverse as Peter Mandelson and Owen Jones. We know from the Beckett Report that Labour suffered the blame for the financial crisis - we're no closer to knowing whether it was a failure to sufficiently distance the Labour brand from the 1997-2010 period or to mount a compelling defence of it that was the problem.

No part of Labour can feel confident in their analysis of 2015 - or in their take on the best way forward for 2020.