Quoting from the South West Trains website…
“Sunday 12, December 2004 sees the publication of the most radical timetable change on the South West Trains network since electrification in 1967. It will mean that your train times are likely to change.
The review has involved the rescheduling of 1,635 trains a day, and we have standardised departure times to help passengers remember them, and come up with a timetable that is easier to use and more robust in the event of a disruption.”
Oh oh… Sounds like trouble to me!