Watching the press conference given by the new Independent Group of Labour MPs, I had an unsettling sensation of deja vu.

Some of us have been here before.

In a box somewhere I still have my red, white and blue certificate as a founder member of a new breakaway group from the Labour Party: the Social Democrats, the SDP.

It was signed by Roy Jenkins, Bill Rodgers, Shirley Williams and David Owen, all ex-Labour cabinet ministers. It was, then as now, a party too young yet to have a single leader. It was a brave, idealistic adventure infused with optimism in an otherwise grey and dismal political scene.

The SDP inspired young people such as me, and millions more who found themselves “politically homeless” in a world where both main parties had lurched to the extremes, captured by their hardline activists, abandoning the “centre ground”. It hit 50 per cent in the polls.

Which MPs defected to form Change UK? Show all 12 1 /12 Which MPs defected to form Change UK? Which MPs defected to form Change UK? Change UK Details on the individual MPs are in the following photos Reuters Which MPs defected to form Change UK? Heidi Allen Anti-Brexit MP for South Cambridgeshire resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Chuka Umunna MP for Streatham since 2010 and prominent People's Vote supporter PA Which MPs defected to form Change UK? Anna Soubry The prominent anti-Brexit MP for Broxtowe resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Luciana Berger MP for Liverpool Wavertree since 2010, resigned from the Labour Party over bullying and anti-semitism PA Which MPs defected to form Change UK? Sarah Wollaston Anti-Brexit MP for Totnes resigned from the Conservative party on February 20 PA Which MPs defected to form Change UK? Joan Ryan MP for Enfield North resigned from the Labour party on February 19 citing its tolerance of a "culture of anti-Jewish racism" PA Which MPs defected to form Change UK? Ann Coffey MP for Stockport since 1992 Chris McAndrew / UK Parliament Which MPs defected to form Change UK? Gavin Shuker MP for Luton South since 2010 Getty Which MPs defected to form Change UK? Chris Leslie MP for Nottingham East since 2010 PA Which MPs defected to form Change UK? Mike Gapes MP for Ilford South since 1992 PA Which MPs defected to form Change UK? Angela Smith MP for Penistone and Stocksbridge since 2010

The SDP too wanted a “new consensus”. Labour had left them, not the other way round: their values were Labour values. The party had been hijacked. They wanted to leave “tribal politics” behind.

Some of those same phrases, and much of the same mood and liberation was on display with the seven rebels who had the guts to put their careers on the line this time round. Fortunately, none said they wanted to “break the mould”, but they may as well have done. They might even manage it: but I doubt it.

With substantial majorities, and barring some nasty local activist attempts at bullying, they could have had jobs for the rest of their political lives. Everything they said was true, just as much of what was said by the SDP founders was true, and appealing.

On Europe, on enterprise, on the social market economy, on Nato and with an emphasis on social mobility and education it was almost like listening to a speech by Roy Jenkins or David Owen back in the Eighties. The main, sad, difference is that back then the term antisemitism was virtually extinct. They are people of principle. They deserve to succeed.

But they face huge challenges.

The new party, whatever it is eventually called, will run into the exact same obstacles that the SDP did.

Mike Gapes: 'I am sickened that the Labour party is now a racist, antisemetic party. I'm furious that the Labour leadership is now complicit in facilitating Brexit'

The electoral system – first past the post – strangles new, insurgent parties at birth: apart from the SNP in Scotland, not since the emergence of Labour in the 1920s have we seen a fresh grouping succeed. The Liberals never quite made a comeback; Mosley’s New Party and Union of Fascists were kept out of parliament, as were, more or less, communists, Trotskyists, the National Front, the BNP, the Referendum Party, and Ukip – as well as the SDP themselves and countless others. At the last election, the two main parties (in England at least), won a record joint share of the vote, not seen for decades – well over 80 per cent.

The new grouping will need to make an arrangement with the Liberal Democrats, themselves the product of the 1988 merger of the Liberals and the SDP.

Yet, anyone who lived through that will tell you that “moderate” parties do not always behave moderately when asked to field joint candidates and write a joint manifesto and have a single leader. There is trouble ahead there for Chuka and his friends, despite the goodwill. Already Mike Gapes dismisses the Lib Dems as an “old party”, and invites Lib Dems to join the new group. They won’t.

One day Labour will, out of sheer electoral frustration, come back to its centre left ground. Jeremy Corbyn won’t last forever and neither will Momentum. Of course, it might take decades, but perhaps it would be better, as Stephen Kinnock says, to fight from inside – not least to push Labour to support a Final Say referendum now.

On the other hand, the SDP helped to create Tony Blair and New Labour by exerting electoral pressure from outside.The Liberal-SDP Alliance won a lot votes, almost pushing Labour into third place in 1983; and, though they scored few MPs, they were a constant reminder to Neil Kinnnock’s party that they needed to get that centrist vote back.

It is true that Corbyn’s Labour Party is more popular than Michael Foot’s was almost 40 years ago, but the signs are that the 2017 election was the high point for its novelty.

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There was much nostalgic talk of Harold Wilson’s reforming progressive party at the Independent Group’s event; oddly echoing some generous words about the last old Labour leader from Corbyn and John McDonnell. It was Wilson’s great achievement to actually balance and include both wings of his party and unite them, rather than trying to suppress the left (as with Kinnock and Blair) or intimidate the right (as under Foot and Corbyn).

What a pity Labour lacks such a similarly unifying figure today.

Just as Wilson managed to keep Tony Benn and Jenkins in the same party (with the young Blair and Corbyn as party members) so Labour now needs someone who could keep Chuka Umunna and John McDonnell on the same team.