A bitter dispute over the role of rail guards has worsened after the RMT union said it had evidence that Southern Railway trains were being cancelled even if staff were available.
Southern services have been disrupted for weeks due to strikes and high levels of staff sickness.
The union has announced a further 24-hour strike next Tuesday, much to the misery of thousands of commuters who travel into the capital every weekday.
The RMT union says it has evidence of 33 trains which didn't run where staff had been available and ready to work. However, services were cancelled because of issues such as engineering works, rolling stock failure or unavailability.
The RMT is protesting against plans to change the role of guards on Southern trains from August so drivers are responsible for operating the doors. A spokesperson for Southern Railway has dismissed the latest claims from the union.