Another thing I've noticed is that 'tiptoptaff' hasn't made any claim to be a rail professional, but perhaps you know him personally and know that he is one.
I wouldn’t call him professional; that might inflate his ego to bursting point!
You say that people are always pleased to give me an answer to any query. Well, they don't appear to have given one to that contained in post #2.
TTT’s post #4 explained that it is because of the shoulder-peak nature of this service that this unit can’t come into traffic. To expand:
The services through Exeter at the time the Cardiff departs can’t be strengthened further. They’re already 3 or 4 car and thus at the limit of what most platforms can accommodate. If you used the unit earlier; it would have to sit around in Exeter station during the peak; and cause more of an operational inconvenience.
While it’s not ideal having a unit sat around on a depot during the morning peak; in ordinary operation it’s the least worst option - and during disruption it’s nice to have a spare on hand that can be used to step up. It also, by being such a late departure, allows Exeter depot to service an additional unit overnight; and save this one for when the departures are going off.
