The core industrial working class backbone of those parties has thus been shipped offshore in the Neoliberal era and otherwise captured by nationalist appeals or who see nothing in it for them to vote for anyone. Social Democratic party leaders in recent decades have thus participated in, and presided over, the destruction of their own organizations and their own erstwhile political-electoral base. And as they allowed the decimation of their own industrial working class, the atrophy and disappearance of the unions as an organized electoral support force followed.
Today neither the class nor the unions existed to deliver the vote for Labour (or for the Democrats, or the Socialist Party, or the SPD, etc.) in strategic contests like the recent British election and Brexit votes.https://zcomm.org/znetarticle/brexit-and-the-collapse-of-british-labour/?fbclid=IwAR2DR7xOpfOvNYbDs-5fw5ksUfVNo6f8Lk_K8-1Rrr26vLP4M-28yo7eGo0