Rail services into the country's busiest station were disrupted for several hours after another signal failure hit the operators of some of the busiest routes in the UK.
South Western Railway trains to London Waterloo were hit by a signalling problem between Putney and Barnes in the morning rush hour, with passengers warned disruption will be affected until mid-afternoon.
Commuters using Waterloo have suffered regular disruption since a three week closure in August as part of an £800 million upgrade of the station and supporting routes.
Most of the problems have related to signalling or points failures, which Network Rail is responsible for.
Mick Cash, general secretary of the Rail, Maritime and Transport union, said: "If it was trade union action disrupting services on a daily basis like this Government ministers would be shouting from the roof tops, but as it is members of their cheerleader organisation, the Rail Delivery Group, they keep quiet and let chaos reign. It's an absolute scandal."
A Network Rail spokesman said: "We apologise to passenger for delays to services this morning on the South Western Railway route which was caused by an earlier signalling fault in the Barnes area.
"Our engineers have fixed the fault. We thank people for their patience and ask them to check before the travel this afternoon."