Bletchleyite
Veteran Member
Probably because of the shear amount of train movements, many which are running late and end up being out of sync. I think the arrival platform is planned in advance but it often never works out because of operating issues. However they should at least the the platform as soon as they know, rather than only announcing it once they open the platform. That seems to be part of the major issue, at Piccadilly they usually let you on the train 20 minutes before departure.
Platforming at Euston is very consistent outside of serious disruption and has been since the Virgin "VHF" timetable was introduced, which is nearly 20 years ago now. Before that the platforms IC trains used were a bit more random, but the Silverlink services were consistent enough that it used to be printed on a sheet of paper and stuck on the pillar in the middle of the Tube exit.
I will never understand why LNR platforms are suppressed, this only started when Network Rail took over the operation of the PIS from Virgin in the mid 2000s, before that they weren't. For Avanti it's partly because of the manual boarding checks - a single common gateline would be a good option to reduce the need.