No, what I mean is that there is a current CP4 project already doing the design work to GRIP4 (single option development, ie they have got beyond choice of options)
to run longer freight trains on this route. It's a subset of a national train lengthening project and already reflects a policy to run longer trains - they wouldn't do that unless it was already proved to be viable.
The work anticipated on the route (as at Mar 2012) is as follows:
Southampton Western Docks Extend Up / Down Docks branch
Southampton Maritime – Redbridge Extend Depot Reception sidings
Eastleigh Provide 775m Up Loop
Wallers Ash Re-site signalling
Oxford Extend Down passenger loop to Wolvercot Junction
Fenny Compton Increase speed of entry / exit to 40 mph
Dorridge Extend Down loop to 775m
Washwood Heath Extend Up/Derby Slow and Washwood Heath Goods Loop to 775m
It is that level of detail that suggests that the trains will happen, the decision isn't pending these trees being investigated.