Let’s say Jeremy Corbyn, broadly through a unification of the party behind a left-wing anti-EU position to rival Boris’ Conservatives and more skillful maneuvering of the anti-semitism debacle, is able to win in a landslide in the 2019 election with 396 seats won. How could Labour have won big like this in areas besides what I described, how would the election have panned out for the other parties (IE would the SNP have won big as they did in OTL or remain more neutered, what happens in Northern Ireland, etc), and what would have been the long term implications of such a large Labour majority rivaling that of Blair?