And hello to Duncan again!
I didn’t have my BAA Handbook at hand when typing my previous replies last last night but now I have I can perhaps shed some light on the eclipse diagram to which you refer.
Diagrams such as these are taken from the NASA eclipses website rather than being generated by the BAA, and there is an explanatory page about them at https://eclipse.gsfc.nasa.gov/SEplot/SEplotkey.html which might help you. It is, unfortunately, worded in very technical terms but the last part should help you understand the various numbers and times around the map. But basically the blue lines are lines of equal eclipse magnitude and the green lines join places where maximum eclipse for that place occurs at the same time. A larger and clearer version of the magnitude/time plot for the UK appears on page 273 of the current version of the Journal, where the text clearly says that the numbers are magnitudes rather than obscurations.
Hope that helps!