Education is increasingly important in understanding political behaviour, including in Great Britain. Graduate status divides British voters on issues (such as immigration) and has led to the emergence of new parties (Reform UK) and the transformation of existing ones (Sobolewska and Ford, 2020). Some argue that it represents a new cleavage across Western Europe (Ford and Jennings, 2020). Extrapolating from the Danish case (Stubager, 2010), we ask if these substantial political differences have resulted in a new social identity, where graduates and non-graduates perceive each other to have opposing interests and to represent an ‘outgroup’. We use a new representative survey of the British public, including survey experiments, to develop a measure of education-based social identity among British voters. Next, we examine the political effects of this identity, finding that it motivates political attitudes, vote choice and candidate preference. On this basis, we argue that the education divide will continue to restructure party competition.