According to the latest polls, the Labor Conservative duopoly that has dominated the UK is evaporating: https://en.wikipedia.org/wiki/Opinion_polling_for_the_next_United_Kingdom_general_election
In fact, in the latest yougov poll, the two largest parties are not conservative and labor, but rather the Brexit party and LibDems, two parties that have centered their messaging around Brexit (LibDems want to remain, the Brexit party wants to leave).
This realignment probably won’t be permanent though, because it revolves around the current political crisis in the UK, and after that crisis is resolved, I expect the political dynamic to return to normalcy. The question is, once that happens, will the Labor and Conservative parties still be main left and right wing parties, or will they be replaced? One possibility is that the LibDems might become the new main left wing party and the Brexit party might become the new main right wing party. The LibDems are far more centrist then the Labor party, however this could change if previously Labour voters make the switch to the LibDems and start influencing that party instead to make it more left wing.
Both the leaders of the LibDems and Brexit party are fans of proportional representation (perhaps because they are both parties that have been previously bullied by the two previous largest parties) and in 2017, Corbyn added proportional representation to it’s manifesto as well, so if the LibDems and Brexit Party replace the Conservative and Labor parties, or even only the Brexit Party replaces the conservative party, then there is also a very real chance that the UK could switch to a proportional electoral system.