whoops, I got that back to front.But the proposed platform numbering is south to north in the station design so GWML westbound are 1 & 2 etc.
not necessarily - not least as they are likely to be quite long anyway. If every other HS2 train stops (which drops back about 6 minutes vs non-stopping - including at OOC which will have longer dwell times than the other intermediate due to higher numbers leaving trains) then they can fit in the gaps. And the GWML will be 4-track from OOC to Paddington (and the Elizabeth line similarly from the portal), allowing trains to non-stop without stopping trains having to wait too long for them to be overtaken.overtaking would lead to huge dwell times for stopping services so stopping is likely to be the norm.
However, while operationally possible to have stoppers and non-stoppers, it complicates things, and it definitely doesn't make transport sense to have a large proportion of HS2 trains not stop at OOC. On the GWML, it's a similar "if you stop some, you might as well stop all" thing. I imagine there will be some trains that run through the station without stopping - the Cornwall sleeper being the most likely, and maybe an early morning or late night HS2 train to get a headline time (Euston-Piccadilly in under an hour non-stop?), but usual practice will be to stop everything.