I've now added a second map which shows the year of peak usage (within the window 1998 - 2023). Some interesting patterns (with my speculations in brackets):
Stations with peak usage in 2023 (black in Map 2):
Lots in Devon and Cornwall (traffic not commuter heavy?)
Elizabeth Line Stations (no surprise)
Cambridge - Ipswich (new trains?)
Norwich - Sheringham (new trains?)
Oban line (think I read about new school travel?)
Stations with peak usage
immediately prior to the pandemic (purple in Map 2)
Most of the country (general pattern of growth halted by COVID?)
Birmingham and Manchester commuter belts
Stations with peak usage
a couple of years prior to the pandemic (blue in Map 2)
London commuter belt (shift to home working predated pandemic?)
Stations with peak usage over 20 years ago (red in Map 2)
A few stations where one really has to worry!
Does anyone else have thoughts about the usage patterns?