I made it to my sofa just in time for the exit poll on Thursday. Home from knocking doors in Dudley North, my plan was to watch it, have a shower and go to bed. I wasn’t much up for reliving 2015 all over again. What’s the point in staying up to agonise over the seats we were going to lose? Better to get an early night, face the grim reality in the morning. That was until David Dimbleby read out the exit poll results.

At 6.45am, with only a few seats left to declare, I turned in.

I was wrong about the result. And like Jess Phillips and many others who underestimated Corbyn and his movement, I’m happy to admit it. Happy, because we have back in parliament some brilliant MPs who I thought we wouldn’t. As Corbyn prepares to announce his shadow cabinet (note that both he and John McDonnell struck conciliatory tones this morning towards former dissenters in the PLP), attention will focus on the make up of his opposition front bench.

McDonnell signalled on Peston that we shouldn’t expect too much change at the top – “why change a winning team?” – was I think the phrase he used. But one significant development that hasn’t yet received much attention is that the Labour party is reported to have expanded our rank and file yet again. Perhaps unsurprising, as I suggested here.

In the closing days of the general election, Jeremy Corbyn told rallies that Labour party membership had reached 600,000. This morning, Paul Mason tweeted that it had increased by 150,000 since polling day. The Labour party of three-quarters of a million is a very different party to the party of a couple of hundred thousand of May 2015.

The party is an institution. Its values and guiding mission are enshrined in the party rule book. Whatever the outcome of any individual election, any individual leader or any grouping within it, the party is the only thing that survives. But in terms of its membership, it is a new party base.

This changes in the Labour party membership over the past two years have been historic; the full consequences of which are as yet unknown. For some, it’s a welcome development. For others, it’s an uneasy unknown that threatens our standing as a democratic socialist party. Some will argue that new members lapse as the world moves on from the election. But for those of us who have been around a long time and remain as committed as ever to getting Labour back into government, it’s crucial that we understand the new membership.

This is especially true for those of us of centrist persuasion. We must ask ourselves: what do we learn from this election campaign that has drawn both new members and unexpected gains across England, Scotland and Wales?

It’s worth us taking some time to work out what parts of the “Old Testament” – that for so long we have lived by – are no longer relevant.

We might start by thinking about how we define our politics. Beginning with ditching the brand of “moderate” – and systematically challenging being labelled as such. There’s nothing moderate about the scale of the challenges facing our country. We’re progressives and we’re radicals or we’re irrelevant.

Let’s not be selective with the evidence to show that, in the end, we are right. I remain a centrist but I want to understand what the centre can learn from an electorate that ripped up the election rule book.

We have an opportunity to build a coalition in the party to take us from 57 seats behind to getting us across the line and into government.

Let’s try to understand the groups that comprise the Corbyn movement within our party to appreciate just what makes them tick. At the very time that they were riding the wave of enthusiasm that to me and many others in the party went undetected, I was ready to go to bed. Before jumping to too many more conclusions, I think I'll instead start asking more questions.

Adam McNicholas was Campaign Director for the Labour party's West Midlands Mayoral bid.