The trains have been converted from the Alstom-built class 460 Gatwick Express trains which are mechanically similar to the existing SWT class 458/0 fleet.

Six eight-car class 460 sets are being converted to class 458/5 five-car trains whilst other class 460 vehicles will be used to strengthen the 30 existing four-car class 458/0 trains to create 30 more class 458/5 five-car trains.

All the class 458/5s will be fitted with through gangways enabling the planned operation as 10-car trains. The programme requires the class 460 conversions to be in use before the remaining units could be taken out of service for conversion - delays to the initial conversion programme prompted SWT to publically criticise contractors Alstom and Wabtec last month as it was jeopardising the overall project.

Together with the transfer of 24 two-car class 456 emus from Southern, the class 458/5 programme will increase the number of vehicles available to SWT by 108 cars. SWT expect the first Class 458/5s to enter service in later this month or next month on services between London and Windsor, with around 15 of the five-car trains in use by December.

Hammond confirmed that studies are now underway to increase platform lengths at Waterloo to accommodate 10-car trains, including the southernmost platforms which are currently limited to eight-car trains. The Department for Transport (DfT) is planning to add capacity for an extra 10,000 passengers per hour at the station at peak times.

SWT also announced that three platforms in the former Eurostar Waterloo International terminal will reopen in the next 12 months to handle Windsor services. Platform 20 has already opened although scheduled use will not start until May. A new pedestrian bridge will be constructed to link platforms 21 and 22 with the main concourse, allowing them to be used for domestic services.