ELECTRIC multiple units built by British Rail in the late 1980s are to get a new lease of life on some GWR routes from next year.

The former Class 319 units, which are dual voltage and constructed by BREL in York for the launch of Thameslink services in 1988, are being fitted with two MAN diesel engines, leading them to be dubbed 'tri-mode' by GWR.

Similar conversions have already been made for Northern.

The Class 769 'Flex' units will run as four-car trains, gaining WiFi and power sockets, as well as air cooling equipment and a revised layout, which will allow more space for luggage.

Porterbrook is leasing 19 of the converted units to GWR, and 19 Class 165 diesel Turbos will then be cascaded to the Bristol area.

Final details of the routes for Flex trains are still being decided, but GWR said 'the fleet will support the introduction of refreshed trains on Heathrow Express services' at first. GWR is taking over the operation of Heathrow Express services under a management contract agreed with the owners of Heathrow Airport.

After that, they are likely to be used between Reading and Oxford, and between Reading and Gatwick Airport via the North Downs Line.

The Flex trains will run in diesel mode on the North Downs Line and between Didcot Parkway and Oxford, although the Oxford route is now expected to be electrified by 2024.

GWR managing director Mark Hopwood said: “We are already delivering the biggest fleet upgrade in a generation, but today’s news shows we have not stopped looking at ways to improve our service for customers by adding extra capacity to our network.”

Porterbrook CEO Mary Grant added: “I am delighted that Great Western Railway have agreed to add our innovative tri-mode trains to their fleet. These trains will offer GWR greater operational flexibility with reduced operating costs; at the same time their conversion and upgrade will see skilled engineering jobs secured in the UK supply chain.”