Analysis by BBC London transport correspondent Tom Edwards

This is horrendously embarrassing for Network Rail. The upgrade at London Bridge is the jewel in its billion pound Thameslink upgrade programme and so far it hasn't worked. 

One rail boss said to me: "They snatched defeat from the jaws of victory."

The new infrastructure - the platforms and signalling - can't cope with the number of trains so they're having to amend the timetable. 

What will worry commuters is this is just the start - there are years left of work at the station.

Already MPs are calling for compensation for passengers. After the problems at Kings Cross at Christmas, Network Rail is having a shocking few weeks. The question is, will there be consequences?

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Network Rail told BBC London's transport correspondent Tom Edwards that commuters should expect more cancelled trains later on Wednesday and advised people to check their service before travelling.

Dave Ward, Network Rail South East route managing director, said: "I'm sorry. We absolutely apologise.

"We thought we would be presenting a new station and a new method of operation after several months of misery leading up to it and that hasn't happened and I'm deeply regretful for it."

He said the "train plan itself, although modelled extensively all the way through, does not appear to be working sufficiently robustly with the new infrastructure".