There are delays on train networks across the capital city this morning.
The fault with the signalling system that caused havoc at London Paddington yesterday is still causing disruption to trains in and out of the station.
Network rail engineers are continuing work to repair the fault, National Rail said.
The rail operator said trains may be delayed by up to 15 minutes or cancelled, Heathrow Connect services are suspended, and some Great Western Railway services will call additionally at Hanwell and West Ealing until the end of service today.
A speed restriction is in place on the approach to London Cannon Street because of a track fault, which is causing disruption to trains running to and from the station.
National Rail warned services may be cancelled, delayed or revised. Disruption is expected until 10am.
An earlier fault with the signalling system between Luton and St Albans has been rectified and all lines have now reopened, however, services running through these stations may be cancelled, delayed by up to 15 minutes or revised. Disruption is expected until 10am.