Isn’t the point of the captive sets that they’re likely to be cheaper than the classic compatibles? As HS2 will be GC loading gauge you could in theory pick up any standard European rolling stock, rather than needing something specially designed to fit our network.
Well the number of classic compatible trains on the HS2 Ltd order is said to be 54.
That's enough for all services including the Manchester trains which will divert to the new leg when it opens beyond Crewe.
All services using the Golborne link and the NPR connections to Liverpool and Leeds will also be c-c, as they run onto classic infrastructure.
The same will be true of anything on the truncated eastern leg to Derby, Nottingham and beyond.
You have the potential for captive trains on Birmingham and Manchester services, but also will have the c-c stock that operated before the Manchester leg opened.
Theoretically, HS2 can take GC gauge stock, but the DfT has not taken an off-the-shelf design and shrunk it to c-c size for the UK - it's a new train.
Scaling that design up for GC gauge, for a limited stock of captive trains, is not cheap.
We'll know more when the construction plans for the c-c stock are agreed, and how the Manchester/Golborne legs navigate the parliamentary process.
If the Golborne link is dropped, there will be a reduced need for HS2 trains (Edinburgh services staying on the ECML).