I do wonder if, on the pre-pandemic thinking, the idea was that the LTS would not be their forever-home? That the 357s were first introduced 22 years ago, and thoughts may turn to replacing them say 2030 onwards, at which point it may have been though that GA could do with a fleet expansion using some identical units if a single (larger) LTS fleet were ordered to replace both classes?They were to ease overcrowding and allow some of the existing 8 car trains to convert to 12 car by redeploying some peak hour workings. I think there is only 74 units of class 357, but loadings had grown and really needed 80-90 units
At the time of ordering (pre Covid) was severe crowding on some services, partly fixed by the temporary use of some 387s, and this was the permanent solution including bit of capacity growth to work alongside the 20 year old class 357 fleet
These are 24m vehicles, so a 10 car formation is about same length as 12 car class 357
I do not know if they will operate as 2 unit peak hour trains as obviously commuting flows have changed dramatically over last 25 months, there might be more sense in using them as single sets where a 4 car unit is too short, but an 8 car set is bit big.
If so, that would be some very rare long term thinking