These unique login credentials happen to be visible right before the 44 minute minute mark in the documentary Nick and Margaret: The Trouble With our Trains. There is also a cropped screen capture of the offending monitor with the machine-produced login which has appeared online, and it does seem to point to a particular workstation on a signaller’s control desk that looks as though it is running the kind of software which controls signals and trains over the final approach to Waterloo station.
It would go without saying that a switch in passwords is long overdue, and I am quite sure that something has already been done about the situation to correct it. Ah well, this just goes to show that we are only human, and with the responsibility of remembering so many personal passwords on our own already, it adds more strain when you have to remember the passwords of others.