My decision on when to draw an entire area in some colour and when only smaller areas or single lines was necessarily a bit arbitrary. However, contrary to the stereotype, the bits in yellow and light blue for the UK do compare to many other regions of Europe (well, not Switzerland). WCML and ECML are completely electrified, so are the London to East of England lines; (most of) the Midland Mainline and transversal lines aren't. See map.
I was much looser with Russia, where my thick coloured strips usually represent a single electrified mainline, but with only branchlines on the rest of the area. *Lunatic*, n. One whose delusions are out of fashion.