The MP has got mixed up about what is happening in a few weeks time. The 2 car 170 services on South TPE (other than the overnight services) will become 3 car 185 services, two of the 3 car 185 diagrams will become 4 car 170 diagrams.
The problem with your idea is ATW and FGW won't be getting any extra stock next year. I suggested an alternative idea in this thread: http://railforums.co.uk/showpost.php?p=1736329&postcount=191 so I won't repeat myself here.
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Well, it is all unravelling slowly. I can't wait to hear what the Minister will actually do to resolve the shortage.
Chinese built diesel units is not the answer as the ROSCOs do not want anymore diesels on their books as many will be freed up in CP5 with a rolling programme of electrification.