A reminder that the reason we ended up here is because 8/700 formations replaced 8/317 8/319 8/321 or 8/365 formations, where there was a significant loss of seating capacity already, further compounded by the 700/0s having excess space devoted to first class compared to all these 8-car formations. This was especially true during the transition period when 700/0s were appearing on existing timetables, so no overall capacity increase - though there’s still routes where overall capacity hasn’t really uplifted at certain times
I'm not sure that's entirely true though because of what the Thameslink-related changes, platform extensions, fixed formations and timetables made possible for the service.
Ignoring the fact that the timetable was a disaster, the introduction of Thameslink meant the twice an hour semi fast (RYS BDK LET HIT SVG FPK) went from mostly 8 car to always 12 car.
The Cruisers were unchanged 8 cars.
But the 700/0s coincided with the lengthening of Foxton P2 and Shepreth P2 and the end of 4 car service on GN. For a brief while in 2018, we went from 1x4 car per hour to 2x8 car per hour! That meant 8 cars not only for us villagers but also for passengers between Knebworth and Potters Bar as opposed to 4 before. We did previously have some 8 cars in the peaks out of London that split at Royston.
After a few years of 700s we got mostly Electrostars back, but as I see it, 8x700s directly replaced 4x365s/317s for a lot of passengers, and 12x700s replaced 8x365s.
It was a shame our half hourly service never really stuck, other than in the peaks, and they extras have now got daft calling patterns (I am sure operationally sensible with the East Coast recast, but terrible for connections other than Kings Cross, omitting both Stevenage and Finsbury Park).