I do try to keep out of involvement in anything other than the historic side of things (honest mods..), but sometimes......So, from times past, pre FG/SWR etc, the 10 car platform extension programme was extremely exhaustive and complex, by the time all non station platform items, such as driver related hop-ups to allow change end to take place at a whole host of locations (everywhere a reversal away from a station platform may, yes
may happen), but in many cases would likely seldom be used, were also taken in to account. This latter a result primarily of non through gang-wayed 10 car formations (455+455+456).
Certain platform extensions were such that the resulting extension was very tight for a 10 car (455+455+456, or 10 car 458/707), due in such cases to infrastructure restraints (bridge parapets/signal position/sighting issues, etc etc), effectively meaning whilst all passenger doors (being at 1/3 and 2/3 positions coach body wise) were safely accommodated, the rear driving cab/door may not be.
But in all such circumstances the guard had an intermediate cab to work from. Here's the rub: prior to the Franchise (as was) change in 2017, AFAIR,
ALL relevant operational information was required to be/and was submitted (to DfT) for other bidders to acquaint themselves of any matters arising, so when it is mentioned (up thread) that it now transpires that a 10 car 701 (no longer physically overall than a 10 car 455/455/456 or 10 car 458) can not operate at certain stations when the guard has to operate from the rear (10th car) cab, this comes as a bit of a surprise, as all the relevant information was there for those who needed to know.
Question has to be asked, in ordering the 701 fleet as a type, which for the record I personally thought was (as far as the SW network was concerned) a step change for the good in passenger and operational terms, did certain 'facts', such as an assumption about DOO (I will say no more), but more crucially other issues partly train to platform interface etc, in certain operational circumstances, just get overlooked/ignored?
Franchise bid work (back then) could be extremely intense, with totally unrealistic deadlines for answers to very complex questions, and so I suspect errors/shortcuts did occur in relation to the 2017 refranchise of the SW network, but only those involved can answer that one!
Some might say now, 'we are where we are'.....
PS: forgot to mention the above comment about 'clever diagramming'.....if those involved in such matters are those I am thinking of, they will be more than capable of finding workable solutions to almost any situation, provided they are allowed to do so.....I will say no more!
PPS:
BOLD added for clarity.