Quote:
"All the sets are 9 vehicles."
All the 91s aka 225s are 9 plus the loco & DVT, but their HSTs do sometimes include 8 car sets (plus 2 PCs). I'm not sure if its fixed but the 8 + 2 sets are often seen on the services running over my avatar (north of Edinburgh).
Generally, they run as in JST's first option, (listed above).
But your question refers specifically to the NXEC livery'ed set, which is full length, tho' (as I've noted previously) even that has been broken and re-formed, resulting for a brief time in a blue-grey-blue-grey-blue formation! (horrendous!)
Glady, its been more consistently 9 NXNE livery'd MkIIIs plus at least one grey PC, tho' only rarely with 2 grey PCs.
And as an aside, isn't it a waste that the DVTs usually run empty, all of them, all day, every day? (Yes, I know the reasons, but isn't it a waste of capacity? Red Star, anyone?)