Genuine question - is that the case if you buy a flexible ticket and have no itinerary?
It's not a simple question!
Most Passenger's Charters state that Delay Repay (or similar) - i.e. compensation paid under NRCoT 32.1.1.2 - is determined by reference to any amended timetable published by the night before.
Therefore it is
ostensibly the case that you would not be entitled to any Delay Repay if trains ran in accordance with an amended timetable. Whether that position would be upheld in Court (in view of section 50 of the Consumer Rights Act, amongst other provisions) is questionable...
However, there is also a right to compensation where NRCoT minima apply - condition 32.1.1.1. In typically vague fashion, the NRCoT do not give any definition of "delayed", however more importantly they do not contain any exception allowing operators to vary the timetable (for the purpose of calculating delays and hence compensation) as above.
NRCoT minima are certainly a lot less generous than most operators' Delay Repay etc. schemes (you only qualify if the delay is 60+ minutes, and only receive 50% of the relevant portion of your ticket). However, NRCoT 33.4 states that:
A Train Company may not be obliged to pay compensation under this Condition if the cause of the delay was entirely outside the rail industry’s control. Each Train Company’s Passenger’s Charter will set out any exclusions that applies to such claims in respect of their services. However, you are entitled to compensation if the delay was 60 minutes or longer, regardless of fault.
And accordingly the minima apply to wider circumstances.
Of course, if you buy your ticket in conjunction with a particular itinerary, the matter is somewhat more clear-cut. But for TOCs to assert that season ticket holders are not entitled to any compensation or recourse when the timetable is arbitrarily slashed with little or no notice, is in Sir Humphrey's words "courageous"!
Culling trains at 22:00 the night before, to pretend that they "aren't cancelled" and thus don't qualify for Delay Repay or count against KPIs, is one of the railway's most anti-consumer and insupportable practices in my view.
If the government gave a damn about providing passengers with good customer service and fair compensation where the railway falls short - which it plainly does not - it would stamp this practice out immediately.