A commuter rail company is to replace 30 of its newest fleet of trains because they keep breaking down.
New trains have proved less reliable than much older stock
The Juniper trains, costing £90 million, were introduced four years ago by South West Trains.
In that time they have have suffered from leaky roofs and failing electronics.
The Juniper rolling stock will be replaced with new German-built Desiro trains, when the lease on them runs out next year.
Figures show the Juniper rolling stock break down every 4,300 miles on average, compared to the previous slam-door trains which broke down on average once every 50,000 miles.
The Desiro trains, built by Siemens, have already proved five times more reliable.
The first Desiros to enter service with South West Trains have gone more than 21,000 miles between faults.
Desiro trains are currently running on some stopping services between Waterloo and Basingstoke, Waterloo and Alton, and Guildford to Ascot.
Phil Haig of Rail Magazine said: "Trains are far more complex now, older trains are far simpler in all aspects. But equally the older slam-door trains have to be phased out by law so South West Trains has little option but to buy new trains."
The Juniper trains were built in Birmingham by French-owned Alstom but have hampered SWT's efforts to improve reliability.
The latest figures suggest that 27% of its services have run late since the trains were introduced.
South West Trains runs services into and out of Waterloo from Hampshire, Sussex, Surrey, and the West Country.