The term “the left behind” proves challenging when it comes to provide an accurate definition. It may be used in reference to geographical areas or to various social groups or both simultaneously. In order to contribute to the better understanding of this concept a discursive approach will be adopted based on the study of parliamentary debates during PMQs. As a communication platform, these parliamentary sessions are efficiently used to promote policies, concepts and ideas. Moreover, the confrontational nature of these debates forces the speaker to constantly readjust his/her speech. More importantly, these sessions have an interrelated relationship offering a reliable frame for the study of the semantic and rhetorical evolution of concepts like “the left behind”. This term is to be found in Boris Johnson’s 2019 manifesto (used 3 times) and during PMQs (more than 20 times during B Johnson’s time in office) but never under his predecessors’ premierships. Our contention is that the term was not coined ex nihilo but is part of a process that started from earlier conservative governments. In other words, “the left behind” would be one of the avatars of a “mythical population” (M. Edelman), that is to say a symbolic category of people (like “the ill-clad”, the “ill-nourished”, “the silent majority”, …), a group that needs to be addressed to and to be made visible through the political discourse. Our contention is that the term “the left behind” represents a semantic element within a larger symbolic category of individuals. These elements forge a new link on an existing chain of terms in so far as they are often reused by new leaders before being replaced altogether. A complex system of semantic echoing between conservative parliamentarians’ speeches is at work. For David Cameron, these groups are the “hard-working people”, a term which then morphed into the “ordinary, working families” and then into the “just about managing” under Theresa May. The “JAM” then became “the left behind” for Boris Johnson before turning into the “most vulnerable” in Rishi Sunak’s speeches at the Dispatch Box. This paper seeks to analyse the main characteristics of the people who are grouped together in each of the PMs’ categories (while determining whether these people are targeted according to the context of situation). It will then try to demonstrate that the designation of these groups results from an evolutionary process throughout conservative governments, and that they are part of a larger symbolic category. Finally, this paper will explore both the political purpose and the effects of using “mythical populations”.