Commuters who use Thameslink or East Midlands Trains (EMT) services are facing a third day of delays and cancellations - and it could continue into tomorrow as well.
A limited train service is running across the Thameslink network, with services being cancelled, revised or delayed by up to 90 minutes. No Thameslink trains are running between London St Pancras and City Thameslink.
National Rail said EMT services between Sheffield/Nottingham and St Pancras are running on a "near normal timetable" - but delays of up to 60 minutes are expected.
Thameslink services between Bedford/Luton and Three Bridges/Sutton/Sevenoaks/Gatwick Airport/Brighton and EMT services between Corby/Nottingham/Derby/Sheffield and London St Pancras International have been affected by signalling problems which were caused by wire damage on Tuesday.
"On Tuesday afternoon, damage was caused to the overhead wires between Luton and London St Pancras International," National Rail said.
"Network Rail were able to fix the wires, but a signalling problem occurred as a result of this damage. We expect this disruption to continue until the end of service today, but it may yet continue tomorrow."
Travel advice is available here.