I am working in macOS 10.12.6
Thanks for the answers. Pity the Properties Toolbar doesn’t kick in automatically when an Image box is clicked - as it does with a Shape.
Other than in ‘Draw’ in ‘Writer’ there is no ‘Position and Size’ item in the context menu, and the ‘Properties’ dialo does not offer a specialized ‘Rotation’ tab.
However, you can rotate an image going to its Properties > Image
tab.