In this article we give a collection of converse Lyapunov-Krasovskii theorems for uncertain retarded differential equations. We show that the existence of a weakly-degenerate Lyapunov-Krasovskii functional is a necessary and sufficient condition for the global exponential stability of linear retarded functional differential equations. This is carried out using a switched system representation approach. (C) 2015 Elsevier Ltd. All rights reserved.