Overnight it was reported that Vince Cable wouldn’t be attending the Lib Dem debate on the economy because he would be busy preparing his keynote speech to conference. As diplomatic excuses go, it wasn’t subtle. In the end he managed to combine both, belatedly joining the debate thronged by cameras, before his turn to take centre stage.

The speech – which you can read in full here – reminds us of Vince’s original roots both in Glasgow and in Labour in the 1970s, though he doesn’t sound overly nostalgic, recalling its “an unhealthy tribalism and a Tammany Hall political machine”. His most severe remarks were (as ever) reserved for the Conservatives, or the ‘hated Tories’ as he labelled them albeit within quotation marks. Referring to David Cameron’s imported campaign strategist Lynton Crosby, Vince condemned their “dog whistle politics, orchestrated by an Australian Rottweiler”.

He also couldn’t resist a poke at David Cameron. Three years ago Vince remarked, after much press comment that he didn’t appear to be enjoying the Coalition very much: “I am told that I look miserable. I’m sorry, conference, this is my happy face.” Last week, he was accused of being a “perpetual Jeremiah” by the Prime Minister for pointing out that the recovery has a long way to go. Here was his classy riposte:

… you will recall from your reading of the Old Testament that Jeremiah was right. He warned that Jerusalem would be overrun by the armies of Nebuchadnezzar. In my own Book of Lamentations I described how Gordon Brown’s New Jerusalem was overrun by an army of estate agents, property speculators and bankers. The problem we have now is that the invaders are coming back. They have a bridgehead in London and the south east of England. They must be stopped. Instead we need sustainable growth.

Vince occupies a unique position within the Lib Dem firmament, feted both by Orange Bookers (for his radical market reforms within higher education) and also by Social Liberals (for his determination to introduce a Mansion Tax). And in his trenchant defence of liberal immigration policies he unites all factions simultaneously. The Scottish Liberal names he invoked were carefully chosen, too, for maximum ideological breadth: from classical liberals such as Asquith, Gladstone and Campbell-Bannerman through to centre-left liberal leaders like Grimond, Kennedy and Campbell. All were placed, alongside Vince himself, in the tradition of radical progressive politics.

So it was no surprise that he rather cheekily deployed a slogan that has more than a whiff of Ed Miliband’s One Nation pitch. Lib Dems, said Vince, should be the unity party:

I want our party to be arguing for the unity of the United Kingdom. But unity is not just about Scotland and England. It is also about north and south. Public and private. Rich and poor. In our tribally divided politics, the country badly needs the one party that can bridge these dangerous divides. This isn’t just a matter of splitting the difference between other parties’ policies but setting out a clear and distinctive vision. The country needs a party which is competent in office but also committed to fighting prejudice and entrenched privilege. We are that party.

An appeal to unity from Vince: Nick will have breathed a sigh of relief at that after the last 24 hours.

* Stephen was Editor (and Co-Editor) of Liberal Democrat Voice from 2007 to 2015, and writes at The Collected Stephen Tall.