I am surprised you have not seen one before but they are an excellent source of information, the older ones have more content. I have 1936, 1954, 1957, 1963 and 1967.
Is the cover screwed on or held by a clip that slides across to free the cover? If this engine is like most other Villiers the difficult part if removing flywheel is resetting timing as there is no keyway, the flywheel is on a tapper.
Alan a good slide show, certainly shows what variety of machinery was at Newark.
Looking at all the photos did raise an ever present question about any exhibit. How and where to put the exhibit number and any other information?