Few people would dispute the fact that Corbynism sought to bring about an ideological paradigm shift in British politics. In this respect, Corbynism represented a serious challenge to the neoliberal consensus that has developed in the UK since the 1980s. However, as this chapter will show, beyond this several ambiguities and disagreements remain over the type of ideology that Corbynism came to represent. What labels should we apply to best describe it? Did it represent something substantively new, or was it, as some commentators have suggested, merely harking back to an older style of Labour politics? Within this debate, Corbynism has been variously described as an instance of “left-populism”, as “socialism in the twenty-first century”, as “class-struggle social democracy”, as “Social Democracy in a New Left Garb”, as “democratic socialist”, as “reformism” but “transformative”, and, as “anti-modernizing” by some and a “concrete utopia” by others. Moreover, it has been denounced by some critics as being too radical in its aims and, by others, as not radical enough.

In our attempt here to unpack the character of Corbynite ideology, we begin by highlighting the multiple ways it has been interpreted by both its supporters and its opponents. In doing so, we tease out some key areas of disagreement between commentators. These include debates over the extent of its radicalism, how it relates to the wider family of left ideologies that emerged after the global financial crisis, whether it should be considered part of the contemporary “populist moment” (Mouffe 2018), and how this relates to its democratic socialism. We then use Freeden's (1996, 2003) popular understanding of ideologies to map the character of Corbynism. In doing so, we argue that, although it is possible to identify core elements of Corbynism as a political project, there remained a sufficient amount of ideological ambiguity to give it a “catch-all” appeal within the broad family of left politics. This “leftist catch-allism”, as we refer to it here, meant that Corbynism was able to mobilize a plurality of activists drawn from different leftist traditions. It also goes some way towards explaining the plurality of interpretations that have emerged within the existing literature.