Delays to trains which lasted all day on Wednesday on some of the country's busiest routes were caused by an attempted theft of cables, it has been revealed.
South Western Railway (SWT) services to and from London Waterloo, the UK's busiest railway station, have been disrupted or cancelled since early on Wednesday, causing travel chaos for tens of thousands of passengers.
SWT said that along with Network Rail it had been dealing with numerous signalling issues in the Havant area of Hampshire.
A message to passengers said: "Upon investigation by Network Rail colleagues earlier today, it was found that there had been an attempted theft of cables.
"This has seriously damaged signalling equipment and has been the direct cause of the signalling issues on the line between Guildford and Portsmouth."
Network Rail will try to resolve the problem overnight, but disruption is expected to continue into Thursday.