GNE most recent response was exactly the same as Arriva very first COVID ramp down, with simply pulling out vehicle workings, which reduced service level at the expense of sensible frequency. (i.e services are running with random gaps currently due to this very urgent approach).

They could have (and in hindsight probably should have) done this again, but I understand the stuff in the planning is effectively a full replan to ensure frequencies and common corridors don't have the same odd gaps that GNE are running now.

That's effectively the difference in the planning time compared to what GNE did and what Arriva are trying to do.