In this study we present measurements, moult data and related observations for 356 Lesser Grey Shrikes Lanius minor ringed during their non-breeding season in Namibia. Our research focuses mainly on addressing critical gaps in knowledge about the species' plumage. We describe non-breeding plumage features that have been omitted in the southern African bird books, and thus provide essential information for accurate ageing. It is noteworthy that birds lacking a black forehead (frontal mask) and those with an incompletely black bill are not necessarily juveniles or immatures, as asserted in the literature and identification guides. These same plumage features are signs of moulting adults and can be observed particularly on the non-breeding, but at times already on the breeding-grounds. Additionally, we offer photographic evidence of the head moult, loss of black forehead and changes in bill colour during the non-breeding season. We discuss the timing and progress of primary moult in adults and first-year birds, along with plumage features for age determination. The study also examines the increase of mass, site fidelity, bird numbers responding to rainfall, and short and long-term fluctuations of population numbers. Our findings contribute insights into the ecology and behaviour of Lesser Grey Shrikes in the non-breeding grounds. Finally, we propose potential subjects for further research to enhance conservation and management efforts. Keywords: Africa, age, bird ringing, errata in literature, Lanius minor, Lesser Grey Shrike, misidentification, moult, Namibia, non-breeding grounds, plumage, SAFRING, sex.