Do TfW have any set plan for where they want First Class to be, like how most London TOCs aim towards London?
I'd say have First Class facing Manchester since at Piccadilly that'd be most convenient for the passengers there, but I'm not good with Welsh stations so not fully sure on where First Class would fit best (Would middle of the train be better for most stations, I think it'd work better for Cardiff?)
It's difficult to tell because of the network TFW work on. Don't forget that the 197's will be maintained at Chester, even though predominantly working South Wales - Manchester (unconfirmed if any other routes). The route to Chester is either via Wrexham or via Crewe, meaning whichever way it arrives will be opposite to the other when arriving into Chester.
Occasionally services run to Carmarthen via Landore/District, without calling at Swansea where it would turn. Occasionally for engineering services turn at east usk when coming off the marches line.
I think the original plan with the mk4's were to keep the loco on a certain end, but that went out of the window within the first week.
Ultimately the 3 car needs to be leading from Manchester into Swansea to detach the 2 car for Milford Haven.
Also some platforms aren't long enough for 5 car trains, so with ASDO, if First is right at the front or the rear of the 3 car train, at some point it will be right at the back and people will need to walk through.