A cartridge (30) for use in a vapour provision system (10) includes an inner container (350) holding a reservoir of fluid to be vapourised, and an outer housing having a mouthpiece (35) formed therein, wherein the outer housing (200) extends in a longitudinal direction along the outside of the inner container for at least a substantial portion of the inner container. The inner container and outer housing are provided with a latch mechanism (500) to retain the inner container within the outer housing.