More than a third of trains between Bedford and Brighton – voted Britain’s worst performing train line – were either late or cancelled during one week this month.
Thameslink have admitted that only 59.2 per cent of services arrived within five minutes of their scheduled time between November 13 and November 19.
And new figures show nearly one in eight (12.2 per cent) were cancelled during the same period.
The worst day was on the Thursday when a “spike in the power supply” between Kentish Town and West Hampstead in north London caused 197 trains to be cancelled.
On two nights this week (Sunday and Monday) Thameslink had to lay on buses to ferry passengers the 50 miles between London and Bedford because they didn’t have enough drivers to operate timetabled trains.
A spokesman for the company said: “We apologise for the cancellations.”
There were also problems at Harlington station on Sunday evening when trains were unable to stop there because of a power cut.
Thameslink was voted worst performing train operator in a survey carried out by consumer group Which? earlier this year.
Only 46 per cent of passengers said they were satisfied.
A company spokesman said then: “We are working hard to improve performance by reducing the delays within our control.”