Today engineering works at Euston. Amended timetable. Signalling is with network rail. This can’t be blamed on timetable.
The problem isn't that there was a signalling failure. The problem is that with an overcomplicated timetable with lots of inter-running and complex crew diagrams, that signalling failure causing a few delayed or cancelled trains knocks on to the whole network, as units and staff end up out of place, until the whole thing near collapses just in time for frequencies to be reduced during the evening.
If you imagine the same situation with separate Euston-Trent Valley-Crewe, Euston-Brum and Euston-Tring/MKC unit and crew diagrams, all you need to do is cancel a round trip on each and everything is back where it should be within a couple of hours. That's why in LM days (even if they did have *some* interworking) if there was an issue in the morning peak it was always sorted by the evening.
Talking of Cheddington, though, I have noticed stop orders being put on, so I'd be surprised if they hadn't.
But I have no issue with them cranking out cheap Advances for through journeys from Euston to Liverpool to fill spare capacity if they feel like (provided they continue to cough up to get the 350/2s out to actually provide it). But these new through services are in many ways comparable to the story of a certain Northern airfield - they are the tail wagging the dog, and they are destroying the service for the core market of short distance commuter and leisure journeys.