Nightsleeper drama on BBC iPlayer-Technical feasibility of train high jacking?

[djsb]

I'm currently watching a Drama called "Nightsleeper" on the BBC iPlayer website.

https://www.bbc.co.uk/iplayer/episodes/m002265y/nightsleeper

The drama features the high jacking of a Glasgow to London train using remote hacking of the train's control systems. When I say features, all we see in the first episode is a removed floor panel in one of the control rooms/cabin. The removed panel then shows some kind of SBC (single board computer as they correctly call it in the episode) that has 2 antennae and a few cables coming from it. The episode ends with the door first being opened and the n closed remotely, and then it's started and driven off, supposedly remotely. We see the driver being locked out of his cab and chasing after the train as it starts to accelerate from the station with passengers remaining on board. They are unable to stop the train.
This has left me asking, I wonder if this is technically possible? Any thoughts?