Locator maps in QGIS print composer

Recently I signed up to become a member of the British Cartographic Society. With my membership I got an excellent book, "Cartography an Introduction" by Giles Darkes and Mary Spence MBE. When I reached the section on locator maps and insets I realised I hadn't posted a video on this topic in some time and there have been a number of updates to QGIS since the last one. Not only do we look at inset and locator maps but also some symbology effects, map themes, adding grids and labelling them using an expression and the freedom to select independent coordinate reference systems (CRS) for map frames and grids.