Waiting on P1 for the 16:12 to Euston, when the departures screens changed to "next train not for public use." A pendolino arrived from the south, stopped at P1 and dropped its pan. Most but not all passengers got off, and three VT staff loaded lots of water and fruit at the first class end. Repeated announcements telling people not to board, then five mins later the driver changed ends and the train departed south again, with just a few passengers on board. No info on the door screens, other than what looked like a head code (1T09), but this doesn't sound right. Can't find it on realtime trains. Anyone have any idea what this service was?