“This is the most profound decision, I think, the British people will ever make.” Alan Johnson, Labour In’s chair, had no qualms about talking up the importance of tomorrow’s vote as he introduced the party’s final major rally of the campaign.

Jeremy Corbyn refused the opportunity to appear with other party leaders, including David Cameron, at an eve of poll rally tonight, but did make a rare appearance with the leaders of the Scottish and Welsh Labour parties, as well as the Mayor of London, this afternoon. Both Carwyn Jones and Sadiq Khan made efforts to distance their May election campaigns from the UK leadership – while Kez Dugdale was much more willing to show an attachment to the Corbyn project in an effort to provide a strong left alternative to the SNP.

Having Labour’s four biggest figures on stage together is an unusual move, but it reflects how important turnout among Labour supporters is to Remain’s chances of winning tomorrow. Particularly, high turnout among Labour voters in London and Wales could be what settles the referendum.

At times, the party has felt peripheral to the campaign at large – partly due, potentially, to Corbyn’s principled opposition to sharing a platform with Conservatives, which has limited his involvement with the official Britain Stronger In Europe campaign.

But as we have got closer to polling day, and polls have shown little between the Remain and Leave, Labour have played a bigger role. Tuesday’s BBC debate was dominated by left wing voices Sadiq, Frances O’Grady, and on the Leave side Gisela Stuart, while today’s rally was one of the few times the Labour campaign has felt comparable to a general election.

The wild applause of a big audience, the big names, the huge banners: Labour have finally entered the campaign with gusto. The organising machine we boast may have been throwing the kitchen sink at it for weeks, but this one of the first signs we’ve had that the bigwigs are joining in.

While the stage may have changed however, the message has not. Khan, Jones and Dugdale kept thumping the same Labour bread-and-butter message we have heard over and over: protect jobs, workers’ rights, security and the NHS by voting Remain.

Corbyn echoed this too, but as always delivered his own, caveated argument. While his speech was less polished and pointed than his colleagues’ – there was a long section about a financial transaction tax – the Labour activists present loved it. And for his ardent supporters, of which there are plenty, the only words that will matter are: “I urge everyone to vote Remain on 23rd June. To get out on the streets tomorrow and make Labour’s positive case for remain.”

This was one of the themes that ran throughout each speech. Khan urged his London audience to “spend every second and every hour persuading your friends and neighbours to vote for Britain to remain in the European Union.”

Carwyn Jones and Kezia Dugdale both mined their experiences of taking on pro-independence nationalists for their addresses, with Welsh First Minister Jones arguing that “going it alone is not in Labour’s DNA”. Under Jones, Welsh Labour claim their success has come from “wrapping ourselves in the flag” to fend off a challenge from Plaid Cymru.

This was certainly evident in Jones’ closing remarks, as he championed an In vote as being “together for Wales – together for the UK – together for the EU”.

Dugdale reflected on her lessons from the Scottish independence campaign, explaining that she understood “what it’s like to campaign hard in the final few days of a referendum vote that will determine the future of our country for generations to come. A campaign that has divided our nation like never before. Where experts are dismissed and facts are a mere inconvenience.”

She said “vote will go down to the wire”, and in a message to undecided voters said: “A Leave vote just isn’t worth the risk.”

A lot of Labour’s rhetoric around this referendum has been dramatic – and the on-the-ground campaigning has reflected that. Now, belatedly, the campaign at the top has started to as well.