Bletchleyite
Veteran Member
On the WCML, you can't go any faster on existing infrastructure due to curvature, especially south of Rugby where tilt squeezes the maximum already, and even a theoretically possible increase from 125mph to 140 in certain very limited locations would have a tiny effect on journey times as well as reducing capacity by opening up a bigger margin between pendolinos and other non tilting traffic on the fasts. The very high frequency timetable exploits current capacity to the full.
One thing that is notable is that had the original WCML 140mph project (PUG2) happened, there would have been significantly less capacity for the present LNR services as these were to be banished to the slows. The only way to then get more capacity would be to go more Crossrail-style and have something like 30tph of 12-car all stations services. The 90 minute journey to London from Northampton would not exactly serve to endear, though.