EXTRA and longer trains could be on the way to ease overcrowding on key commuter Rail services between Oxfordshire and London.

And the Cotswold Line from Oxford to Worcester could also benefit from the return of Class 180 Adelante trains, which worked most services on the route from 2004 to 2008.

Train operator First Great Western has issued a tender invitation to rail engineering firms asking them to lodge bids to refurbish up to six of the five-coach diesel Adelante trains.

It also wants to convert at least 20 coaches, mostly redundant buffet cars, to lengthen High Speed Trains, adding about 80 extra standard class seats to each unit.

FGW estimates that the work could cost up to £10m.

Under a rolling stock plan drawn up by the last Government, FGW’s Thames Valley routes were expected to get 50 extra diesel multiple unit coaches but the plan was dropped when it was decided instead to electrify services between London Paddington, Reading and Oxford by 2016.

However, according to surveys by the Office of Rail Regulation, FGW has the worst overcrowding problems of any rail company in the UK .

The firm has been in talks for several months with the Department for Transport about ways to provide extra coaches during the next five years until electric trains become available.

An FGW spokesman said: “Since the beginning of our franchise we have significantly increased capacity on many of our routes.

“However, with more and more customers choosing to use our services it is difficult for us to keep up with demand.

“I can confirm we are working with the Department for Transport to evaluate a number of possible options for increasing capacity in the Thames Valley area, including lengthening our seven-coach HST sets by adding an extra standard class carriage and the introduction of some Class 180 units.

“We recognise there is a real need to improve capacity in key areas of our network, so this evaluation is about understanding the costs and benefits associated with these plans.”

The return of Adelante trains on FGW services would represent a U-turn by the firm. It withdrew them from service in March 2009, blaming poor reliability and high operating costs compared with its HSTs.

FGW announced on Wed-nesday that it would not to take up an option to extend its franchise for three extra years from 2013 and would instead bid for a new deal from the Government.

However, managing director Mark Hopwood pledged it would be business as usual until the end of the current franchise agreement in 2013.