Network Rail is to be investigated by Britain's rail regulator after it was accused of delivering poor punctuality and reliability on some of its key routes.
The routes, some of which are the busiest commuter routes in the country, were "below requirements", according to the regulator, the Office of Road and Rail (ORR).
They are operated by Southern, Thameslink and ScotRail.
This will come as no massive surprise to commuters travelling into London Bridge, which has been thrown into chaos by long-term refurbishment, as well engineering works at King's Cross and Paddington causing major delays over the Christmas period.
Facing cost overruns and problems with reliability, Network Rail defended its network, saying it was the "safest in Europe", while acknowledging there were "opportunities to improve".
The ORR said that 89.6 per cent of trains were on time - less than the 92.5 per cent target. It did acknowledge, however, that Network Rail has had to deal with increased demand - with passenger journeys increasing by 59.1 per cent since 2005.
Chief executive Richard Price stated that it was investigating the firm's "performance improvement plans and delivery of enhancements".
Network Rail said:
There are clearly opportunities to improve following decades of under investment in the rail network. However, it is worth highlighting that we operate the safest passenger network in Europe and the railway asset reliability is the best it has ever been.
The increase in passengers means that more people are getting to their destination on time than ever before.
Transport secretary Patrick McLoughlin said:
I expect the regulator to hold Network Rail to account, performance must and should improve. The industry has to work together to address these failings and deliver for passengers and the economy, that needs to start now.