The old Labour establishment’s loud objections to Jeremy Corbyn’s reshuffle betray a belief that shadow cabinet members have a moral and democratic right to their jobs. Had Corbyn, like almost any party leader in history, appointed a shadow foreign secretary who shared his foreign policy, dismissing Hilary Benn would have prompted even more outrage from Labour’s centrists.

The outrage has no democratic basis. The power to reshuffle and remove shadow ministers is, to be sure, a power from above, but it has been granted to Corbyn by the biggest popular mandate any Labour leader has ever had. Michael Dugher, Pat McFadden, Hilary Benn and Maria Eagle, on the other hand, were not elected by anyone to speak for the Labour Party as a whole. Their only mandate is from their constituents, which gives them the right to a seat in the Commons for the duration of this parliament, not a place in the shadow cabinet.

An unjustified sense of entitlement is also evident in the argument over whether sitting Labour MPs should continue to be automatically reselected, whether or not they maintain the support of their constituency parties. Any mention of reselection or deselection has been met with such hysteria that Corbyn has been forced to distance himself from attempts to make MPs more accountable to the membership.

The belief in the impunity of sitting MPs is so strong that even the act of lobbying them has been classified as bullying and intimidation. When Momentum organised its supporters to write to Labour MPs to ask them to vote against air strikes in Syria, several Labour MPs called for it to disband. The group was also held responsible for any and all abusive emails sent to MPs, by anyone. Stella Creasy’s house was widely reported to have been ‘targeted’ by a ‘mob’, until Creasy herself said that the story wasn’t true.

As many generations of Labour activists and onlookers have observed, the binding assumption that underpins the old guard of the Parliamentary Labour Party is not democratic but aristocratic. They may not have been born to rule, but they are certainly not going to let anything so frivolous as the will of the party membership determine whether or not they keep their seats in parliament and on the front bench – jobs which are theirs by some supra-democratic right. Even the language in which the events of the past ten days have been framed – as the ‘revenge reshuffle’ – has situated them not as part of a collective political project, but as a struggle between warring individuals. There are many ways to describe this approach to political legitimacy, but ‘forward looking’ and ‘modern’ are not among them.

‘Modernisation’ in the Blair era was a euphemism for rightward drift. Many of those at the heart of the New Labour project understood that support for privatisation or tuition fees was only possible if decision-making powers were walled off from the party membership. But for many others, constitutional reform was one of the pillars on which the rational new order, free from the old ideology, was supposed to be built. Voting reform, House of Lords reform, devolution – all were supported by many on the right of the party and sometimes opposed by those on the left, who saw proportional representation as a route to locking Labour into a centrist alliance with the Liberal Democrats.

How can the standard-bearers for the New Labour project claim to represent the forces of modernisation if they cling so fiercely to an out-of-date conception of their own legitimacy? How can a broader layer of centrists in the party advocate reforms in the way the state is run if their only hope of success in factional terms rests on being unaccountable to their overwhelmingly left-wing membership? And, perhaps most important, if constitutional and voting reform can no longer credibly be driven by the right and centre of the party, who will champion them?

It is up to Corbyn’s new Labour left to lead the way on constitutional modernisation and democratic reform, in both the Labour Party and the state. John McDonnell has been openly voicing his support for proportional representation for months – and for good reason. In recent years, the economic crisis has gone hand in hand with mass disenchantment with the political mainstream. Solving these crises – advocating a new constitutional order as well as an economic one – is not just about gaining tactical advantages in Labour’s internal power struggle, or being seen to be the voice of the future. It is also the right thing to do.