Published: 12:00 PM February 21, 2019 Updated: 8:45 AM September 18, 2020

It's finally happened. After more than two years of dithering and indecisiveness, the UK has a new sort-of-but-not-quite political party.

Labour MPs Chris Leslie, Luciana Berger, Chuka Umunna, Gavin Shuker, Angela Smith, Mike Gapes and Ann Coffey have announced their resignation from the party. Picture: Stefan Rousseau/PA

On Monday, seven MPs finally made the decision to quit Jeremy Corbyn's Labour party, with another following the next day, citing concerns over the party's institutional anti-Semitism, its political direction, and its position on Brexit – in roughly that order.

Rather than immediately form a new political party, the MPs have for now opted to sit as a group of independent MPs, though they have launched a website with their principles – vaguely-worded but largely agreeable pledges, with few specifics and no mention whatsoever of Brexit – and thus have something of a shared platform.

What the move actually means, and what's driving it, isn't immediately apparent, so here's an effort at decoding what the whole effort is actually about, and what it might mean for UK politics.

The first thing to note is that while all eight MPs who have formed the new grouping are Remainers, and support a People's Vote, they have not made this the centrepiece of their defection – and the People's Vote campaign has offered them little to no public support, given its slim hopes of success still rely on somehow changing Jeremy Corbyn's mind on backing a second referendum.

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The reality is that any new grouping would have to seek to move beyond Brexit as the rationale for its existence, particularly because it is possible that in less than six weeks the UK could have left the European Union – and rejoining at that point in the short- to medium-term is all but impossible, as it would require signing up without the rebate, entering the Schengen free movement area, and preparing to join the euro.

A new political movement grounded on internationalism and many of the principles that guided the EU might be viable – or may not, we will see – but it cannot be a 'stop Brexit' party. If such a thing was ever a good move, its time was a year or more ago.

If this new grouping picks up more defections from Labour or other parties, it could become a powerful force in shaping the UK's future relationship to the EU – steering it towards a Norway-type deal, rather than a harder Brexit – but it will have to be defined by more than that.

Perhaps the next most confusing thing about The Independent Group – the new group's name – is why it isn't simply a new political party. Those who remember when the Gang of Four left Labour in 1981 might note that a similar approach was taken then: the group (which only included two sitting MPs) quit without immediately forming a new party, and took a little time to gauge support, and how many others might follow. Quitting in this way, with only a vague set of ideas to create a largely informal group, might initially seem odd – but might best be seen as a bid to flip the table, to at least shake things up and see where the dust settles.

Depending on how Labour reacts, or how May reacts – or even how the Liberal Democrats react – there could be cascade effects which start to see a collective mass of MPs begin to move.

As some lobby journalists have noted, if the grouping could start to approach a few dozen MPs it would begin to have a chance of overtaking the SNP in parliament (the threshold of 36 here is still some way off, though) and thus pick up its weekly two questions at PMQs.

At that stage, such a movement may start to seem viable as a full political party, perhaps in alliance with – or even supplanting entirely – the Liberal Democrats. Similarly, the move could fizzle entirely: Labour's right-flank, and also the sizeable body of MPs demoralised by the leadership's apparent lack of resolve in tackling anti-Semites, racists, and cranks, have proven woefully ineffective at curbing such excesses, and shamefully tolerant of many of them.

After years of being ground down, it's not clear why they would move now – and Labour tribal loyalty is a powerful force for its many MPs, staffers and activists who have grown up with the movement since childhood.

One possibility is a slightly counter-intuitive one: Labour's Twitter army of abusive and sneering trolls – most of whom hide behind anonymous accounts and a few of whom get numerous television appearances thanks to their barely-watched YouTube channels – are narrowly correct when they note few of the initial eight Labour quitters would be likely to win their seats against Labour as independents.

This charge, they should note, makes their other accusation of 'careerism' total nonsense – but basic logical consistency rarely troubles this crowd.

What a new movement could do, however, is challenge Labour hard in other seats – pro-EU Labour marginals, urban centres, and more, and could spell the difference between victory and defeat in plenty of them.

Labour has found it very easy to be complacent about pro-EU votes, knowing that for many the Liberal Democrats are a busted flush and Conservatives are not an option. The result has been a leadership willing to ignore the will of its MPs, the will of its members, and the will of its voters, and push for Brexit.

Perhaps perversely, the defection of eight of its most pro-EU MPs makes that harder: if they can get even a small amount of momentum behind them, Labour might be forced to take the threat seriously and finally listen to what its voters want. That – more than victory at the ballot box – might be the most seismic thing the new movement could do.