Watch the track ahead for people/obstacles, stop train in emergency, push stat buttons, push open/close door buttons, drive the train when automatic operation is withdrawn (every weekend as a minimum on some lines), rectify faults onboard the train, move the train when it stops, responsible for the safety of all passengers (upto 1000 per train) in an emergency.

It can be a lonely and disorientating job, and has a limited time left.

London Underground are developing/investigating many technologies to automate all of these points.

BTW I am not a Tube driver!