From The Brighton Toy and Model Index

Image from a long foldout single-sheet MINIC vehicles leaflet/mini-catalogue. This catalogue is incomplete, but all the images are present (in different order!) on a 1937 catalogue, including some that aren't on Bartok's reference 1936 strip catalogue, so this we're provisionally dating this 1937, with a rider that it might be a "partial" 1938 or 1939. Regarding the individual images, since they're all on the '37 catalogue, referring to them as "1937 images" seems appropriate.