But trains arriving from the sidings to P1 or P3 at Oxford dont show this behaviour, and on approach this train shows the correct destination on the CIS▸ , it only changes from Great Malvern to Not for public use when the train gets to the end of the platform. It does catch a lot of people out especially on a friday afternoon when you get lots of weekend travellers.
The reason it doesn't usually happen on platforms 1/3 at Oxford is that the signaller doesn't input the headcode into the system until it is in the platform. The sidings are not track circuited so they don't have specific berths where that would be done, hence all the
PIS▸ sees is the trains proper passenger headcode suddenly popping up in the platform. If an
ECS▸ working was coming from, say Worcester, to form an outgoing passenger departure then exactly the same would happen on platform 1 or 3 as does with the 17:31 to Worcester's, but that is very rarely the case.
At other locations, such as Reading, there are signals between the sidings and the station so they have to be set-up into the signalling system as a Class 5 for their progress into the station and that is where the system gets confused (as it does with your example at Platform 2, Oxford) as a Class 5 headcode enters that signal berth as it passes the previous signal.