Great Western Coffee Shop

The long awaited news of the merger of the GatEx fleet into SWT's 458s.  This probably means the end of 458s at Reading, to be replaced by 450s, with the 10 car 458/460 trains running on the routes to Weybridge, Windsor, Hounslow Loop etc.

http://www.dft.gov.uk/news/press-releases/new-platform-and-60-extra-carriages-for-waterloo-commuters

^The additional carriages will enable trains on the following routes to be
lengthened from 8 to 10 cars: Waterloo-Windsor & Eton (Riverside),
Waterloo-Weybridge via Brentford and Staines, Waterloo-Hounslow via both
Richmond and Brentford. This will be achieved through the introduction of 60
Class 460 vehicles.
^An internal cascade will provide two additional Reading and one further
Hounslow peak service into Waterloo; and further lengthen seven South West
mainline services. South West Trains expect to complete the rolling stock
deployment by July 2014, with the first 10-car service operating from May 2013.

The seven mainline services SWT expect to be strengthened are as follows:
Morning peak
Southampton Airport Parkway to Waterloo (8 car to 12 car in high peak)
Portsmouth Harbour to Waterloo via Eastleigh (5 car to 10 car in the peak)
Southampton Central to Waterloo (4 car to 5 car in the peak)
Evening peak
Waterloo to Poole (5 car to 8 car)
Waterloo to Portsmouth Harbour via Eastleigh (5 car to 8 car)
Waterloo to Portsmouth Harbour via Eastleigh (8 car to 10 car)
Waterloo to Alton (8 car to 12 car)

Paul

Though the DfT's press release contradicts itself as it states (with my highlights):

Their arrival will mean that services from Windsor, Weybridge (via Staines), Portsmouth, Southampton, Eastleigh, Reading, Hounslow and Alton into Waterloo can be lengthened and additional services will also run from Reading.

So that would hint at 10-car trains to Reading, but then that's not mentioned in the following quote that Paul posted above.

Yes, there are no current plans for 10 (or 12) car to Reading, because the platforms between there and Virginia Water are not being extended.  However they are likely to fit SDO to the mongrel units, as it is needed on the Windsor route - so it is possible that occasional 10 car trains could be run to/from Reading.  (For an unlikely precedent, there's an evening peak Portsmouth Harbour to Waterloo via Eastleigh that runs as 12 car - on leaving Portsmouth & Southsea the rear unit is inaccessible until Eastleigh!)

But I suggest it is more likely to be an uncontrolled DfT 'spinner' who has misread something...

Paul