Will Brexit pave the way for a new party to make a splash as the Liberal Democrats and Ukip once did? That’s a source of hope (and fear) to some at Westminster: that a bad Brexit will pave the way for either a party of Remain or a Ukip 2.0 to surge in the polls and either hold the balance of power or do electoral damage to the big two?

The potential of Brexit to either deliver a major economic shock which leads to a political shock, or simply to cause a political crisis is very high. The promises made by Vote Leave in the referendum, and repeated by the Conservative Party, cannot easily be reconciled with another, so either you try to do so and cause an economic shock, or you abandon some and open yourself up to accusations of “betraying Brexit”. Either way, the potential for a new party, or for Ukip to have a revival, is high.

There’s an important Brexit-related block on any new party’s growth, and it’s this one: when we leave the European Union on 29 March 2019, we will cease to participate in European parliamentary elections, the only UK-wide proportional elections we hold. First-past-the-post, which we use for parliamentary and local elections, is very punishing to new parties. One of the reasons why the last few years have seen the successful development of new parties – not only Ukip, whose success of course helped trigger David Cameron’s referendum gamble, but the Greens, who now have a parliamentary seat at Westminster – is that non-established parties were able to get a foothold, and crucially a measure of financial stability which allowed them to survive and thrive.

Although there are still proportional elections held in parts of the United Kingdom – London, Scotland and Wales all have the party list system – they are all, for reasons that should be obvious, not ideal incubators for any new party seeking to make waves in England, which due to its greater size is where these parties have to make a breakthrough to really challenge for power.

That’s not to say that a new party won’t emerge, but it is worth noting that the only new party to enjoy even partial success in the era of mass suffrage without benefiting from the proportional system of the European Parliament is the SDP, which included more than 30 Labour MPs and four former Cabinet ministers.

It is worth noting, too, that because any new party will have to do well in one of London, Scotland or Wales’ proportional systems, it will limit and alter both the type of party that emerges – and where power in that party lies.